Miraculous: Les aventures de Ladybug et Chat Noir

After stealing the Miracle Box, Shadow Moth turns into Monarch and uses the Rabbit Miraculous to return to a vulnerable moment in Ladybug and Cat Noir's past to capture their Miraculous.

Convinced that Gabriel's coldness towards her stems from a misunderstanding, Marinette decides to have a heart-to-heart with the father of the boy she loves… and her outstanding courage inspires her friend Kagami! She too would love to open the door to her ever-commanding mom's heart! Alas, the conversation comes to a sudden end when an unexpected guest returns and spirits Kagami away! Who is this mysterious guest? Will Ladybug and Cat Noir save Kagami? And will Marinette and Adrien ever have a chance to love each other freely?

Lila is an accomplished liar. This evil talent has allowed her to be loved by all, and even to be hired by Gabriel Agreste. But Marinette and Adrien's growing closer pushes the boy's father to name Kagami as the new face of his brand, enraging Lila. She uses an incident in class to call for new elections in order to replace Marinette as class representative. But the campaign goes wrong, much to Monarch's delight. Thread lightly, for with Lila, things are more than often not what they seem…

The end of secondary school is approaching and Lila & Chloé have to defend their classmates futures in front of the class council. Marinette is worried. What will be the next evil plan of the 2 villains?

Marinette is formally introduced to Master Fu, whom she knew as Tikki's healer, learning that the man is the last Miraculous Guardian due to a past mistake he made that destroyed his temple with the Butterfly and Peacock Miraculouses lost in the chaos. Fu reveals the book Marinette brought to be a spell book covering Miraculouses, suspecting its owner could be Hawk Moth, with Marinette fearing Adrien could be the masked figure. But she learns from her classmates that the book belonged to Adrien's father Gabriel, who prevent Adrien from going to school for losing the book. Marinette heads to the Agreste estate as Ladybug, finding out that Gabriel had been akumatized into "The Collector", a supervillain with the ability of trapping anything that touches the pages of his blank sketchbook. After Ladybug and Cat Noir eventually defeat and restore Gabriel, Marinette and Fu concludes that he cannot be Hawk Moth. Fu copies the book's contents onto a smartphone before Marinette returns it to Gabriel, admitting that she was the one who held the book, not Adrien. Gabriel reveals that he obtained the book while visiting Tibet and that it is a memento of his wife, rescinding Adrien's grounding as he returns to school to the joy of his classmates. But Gabriel is revealed to have copied the book along with being Hawk Moth, having akumatized himself as a ploy to cover his tracks.

After Chloé sets off a false fire alarm forcing the entire school to do chores as punishment, Adrien scolds Chloé, telling her that she needs to be 'nice' to people if she wants to remain friends. Chloé's butler, Jean, has her host a party for everyone and encouraging her to what her old teddy bear would do. Confident, Hawk Moth sends an akuma beforehand. During the party, Chloé tries her best, but when seeing Adrien dancing with Marinette, Chloé loses her temper and Jean accidentally reveals her teddy bear to everyone, leading Chloé to embarrassment and fires him in the kitchen. Feeling vengeful, Jean is then targeted by the akuma, and turns into "Despair Bear", a doll-sized villain who has the ability to manipulate anyone he touches inside a small teddy bear in which he controls.

Marinette has to babysit Manon, but realizes Ladybug has to interview for a television show Face to Face, so she invites Alya over and excuses herself to help her parents downstairs. Realizing she needs higher television ratings, host Nadja resorts to asking about Ladybug and Cat Noir's romantic relationship, which causes Ladybug to storm off, dragging Cat Noir along with her. The studio is dissatisfied and cancels Nadja's show. Laid off, Nadja gets akumatized, and Hawk Moth turns her into "Prime Queen", a haughty reporter whose ability to teleport through television screens and posters; she creates a show in order to capture the two heroes, going to great lengths to prove that Ladybug and Cat Noir is truly in love.

Marinette is excited because today is her birthday. Not only that, but her grandmother, Gina Dupain, is also visiting. Despite being excited to visit Marinette, Gina is surprised to see how much Marinette has grown up, but is saddened when Marinette does mostly new things. While hanging out, Marinette heads to where her friends planned her surprise party and ditches Gina. Thinking she was rejected, Gina is akumatized by Hawk Moth, turning her into "Befana", a motorcycle baddie with the ability to turn people who do bad things into coal and those who do good into angels, who become her servants, with a gun filled with candy she wanted to give Marinette.

On the fencing court, Marinette has hopes of joining to impress Adrien. Armand assigns the new recruits to pair with the experienced ones. A new student, Kagami Tsurugi, the daughter of a famous fencer, moved in Paris and challenges Adrien to show everyone she's the best fencer. After the duel, Marinette; the referee, unsure how the battle ended, due to Kagami chasing Adrien around and battling roughly, declares Adrien the winner, much to Kagami's dismay and humiliation, causing her to depart from the school. Hawk Moth akumatizes Kagami, and turns her into "Riposte", a silver armor samurai villain with the power to slice and cut anything in half with one armed saber. To make matters worse, Adrien hurts his leg and has to cover it while helping Ladybug as Cat Noir at the same time without revealing his identity.

When Max builds Markov, a miniature robot capable of real human emotions, he is hesitant to even reveal him. After helping prevent a computer virus from wiping the school's servers, Principal Damocles instead confiscates Markov, thinking that he's a toy. Separated from his friend, Markov even becomes akumatized, and Hawk Moth converts him into "Robostus", a techno-threat capable of giving life to mechanical devices. When Hawk Moth tells Robostus to bring him the Miraculouses, he mistakenly informs him of their power to grant wishes. Robostus takes Max with him in his new mega-sized body to the stadium, where he ambushes Ladybug and Cat Noir. When Robostus is about to obtain the heroic duo's Miraculouses, he intends to take them for himself to gain mortality; only for Max, wanting his friend back, to free Ladybug and Cat Noir, who capture and de-evilize Markov. Marinette later asks Master Fu, who elaborates the Miraculouses' ability to grant wishes. Due to the universe needing to maintain balance who ever is granted a wish, someone else must lose the very thing wished for. Marinette promises Fu to not allow this, and continue guarding her own Miraculous.

Today is a great day for Marinette: she and her friends, Mylène, Rose, Juleka, Alix and, of course, Alya, have come up with a flawless plan to help Marinette propose a romantic stroll to Adrien. But nothing is going as planned and Adrien's bodyguard, annoyed by the girls, becomes Hawk Moth's target. However, while the latter tries to akumatize him, the bodyguard calms down when he sees Adrien. Instead, Hawk Moth has to deal with something unexpected: the akuma goes and transforms a young baby child, who is upset and crying, turns into "Gigantitan", a fifty-foot (disobedient) giant baby, who would stop at nothing for a lollipop!

Principal Damocles starts cosplaying his favorite hero, Knightowl, and tries to act like him in real life as well. However, he becomes the laughing stock of Paris when his heroic exploits go horribly wrong and accidentally reveals his identity from his heroes. Humiliated, Damocles is akumatized by Hawk Moth and transforms into "Dark Owl", who has real superhero powers. Dark Owl manages to trap Ladybug and Cat Noir in a chamber where they will drown unless they hand over their Miraculouses, which would also mean revealing to each other their true identities. With Ladybug not ready to know that yet, they de-transform with their eyes closed, unaware that Tikki and Plagg see not only each other but also learn the identity of the other's owner. The two kwamis feed each other, so Marinette and Adrien can regain their powers, while they trick Dark Owl and Hawk Moth by giving them fake Miraculouses made out of salt dough. Ladybug and Cat Noir eventually defeat the owl-themed supervillain, and then help Mr. Damocles to become a superhero on a smaller scale by doing good deeds.

Marinette, Alya and her other friends go to eat some ice cream together at a cart owned by André, a famous ice cream maker in Paris. According to a legend, the couple who eats an ice cream at André's place will love each other forever! Marinette hopes that Adrien will be there, but he did not come. For a good reason: he transformed into Cat Noir to prepare a candlelight dinner for Ladybug. Disappointed in Adrien's absence, Marinette refuses to eat the ice cream André gave her. Depressed over the failed romance, André becomes akumatized by Hawk Moth and shapes into "Glaciator", a giant ice cream snowman who solidifies 'single people' into ice cream and they start to melt! Ladybug and Cat Noir must not get cold feet if they want to stop him. In the midst, Marinette comes to know Cat Noir's genuine and sensitive side.

Marinette helps Alya babysit the latter's twin sisters, Ella and Etta. When they keep staying up and refuse to go to bed, Alya forbids them from going to the amusement park the next day and confiscates one of their hats. The twins, sad over the fact they now can't go the amusement park and have to listen to their older sister's orders, are fighting over the other hat, then Hawk Moth akumatizes them both into "Sapotis", a pair of small but totally unpredictable monsters that multiply and cause havoc. When Ladybug and Cat Noir are overwhelmed by the creatures, Ladybug is prompted by her Lucky Charm to visit Master Fu, who loans her the Fox Miraculous. Ladybug gives the Miraculous to Alya, who, with the command of Trixx the kwami, transforms into the fox-themed superheroine, "Rena Rouge". After the three heroes overcome the Sapotis menace, Alya reluctantly returns the Fox Miraculous to Ladybug and keeps the details of her adventure a secret. However, a new superhero made Hawk Moth realize that there are more Miraculouses in Paris, as well as their Guardian.

Aurore loses a contest and is transformed into Stormy Weather, and Ladybug and Cat Noir must halt her evil ways so that sunshine can return to the city.

It is Adrien's birthday and Marinette is struggling to give him the present she made for him. When Adrien's father, Gabriel Agreste, a secretive and renowned fashion designer, won't allow Adrien to have a birthday party, his best friend, Nino Lahiffe, gets mad about how unfair he's being towards Adrien. Claiming that all adults want to stop kids from having fun, Nino is tempted by Hawk Moth and becomes the "Bubbler", a villain who sends all the parents into outer space through his bubbles. With the villain defeated, Adrien receives a scarf from Marinette, but thinks it's from his father thanks to his assistant Nathalie who threw the letter she made.

Attempting to ask Adrien out to the movies over the phone, Marinette instead accidentally leaves behind an embarrassing voicemail and rushes to delete it before he listens to it. Meanwhile, a sculptor named Théo is displaying a statue in the park, which he built in honor of Ladybug and Cat Noir. He has a crush on Ladybug and is looking forward to seeing her at the unveiling event, but only Cat Noir ends up arriving. After the event, Cat Noir insinuates to Théo that he and Ladybug are a couple. Feeling jealous, Théo is tempted by Hawk Moth and transforms into "Copycat", an exact replica of Cat Noir, to frame the original for committing crimes.

Marinette's parents are celebrating their twentieth anniversary, leaving Marinette to take care one of her father's special cake requests. However, she gets a call from Alya, who reminds her to bring a banner she made for a race between two of her classmates, Alix and Lê Chiến Kim, and she rushes off to Trocadéro. Alix has received a family heirloom pocket watch for her fifteenth birthday, and passes it to Alya to safeguard it for her while racing. However, during the race, the watch passes hands multiple times, before it is dropped by Chloé onto the ground and skated over by Alix, destroying the watch. Angry at her friends, Alix is attracted to Hawk Moth's akuma and turns into "Timebreaker", a speedy villain who freezes people and fades from existence with a touch to get energy to travel back through time. To make matters worse, Marinette forgot to return to her baker shop to deliver the cake so by chance, Ladybug goes back in time with "Timebreaker" to resolve all the problems because of a broken watch. Not to mention that both Hawk Moth and later Cat Noir has to deal with two "Timebreakers" and two "Ladybugs"!

A fashion competition is to be held at Collège Françoise-Dupont where the winner will have their derby hat worn by none other than Adrien. Marinette is determined to win in the hope that Adrien will then notice her. Meanwhile, Roger Raincomprix, a police officer, orders a pigeon-loving man Xavier Ramier, to stop feeding the pigeons and leave the park. Dejected, Xavier is akumatized by Hawk Moth and becomes "Mr. Pigeon", a supervillain who controls massive flocks of pigeons. While Ladybug has to make due time in knitting the hat, Cat Noir has to deal with his allergy to feathers.

As Ladybug's biggest fan, Alya is out to expose Ladybug's true identity when she finds the self-centered Chloé Bourgeois with Ladybug's "yo-yo and mask". When Alya attempts to take a photo of Chloé's open locker for evidence, Chloé accuses her of invasion of privacy, and has the principal suspend her. Sad of not getting in touch with Marinette, Alya is akumatized by Hawk Moth and becomes "Lady Wifi", a villain whose smartphone can fire different icons such as pause and lock, can travel through wifi-serviced phones, and will stop at nothing to expose Ladybug, including invading Chloé's apartment.

Marinette accidentally drops her history textbook while transformed as Ladybug. Alya, who happened to be at the scene, trying to film Ladybug in action, picks up the book, and speculates that Ladybug could be a Parisian collégienne. Marinette starts to panic when she finds out, and by Tikki's suggestion, brings Alya to visit a new Pharaoh exhibition at the Louvre, in order to try to get the book back. As they arrive, Alix's brother, Jalil Kubdel, is discussing with his father about how one of the exhibitions on display is a resurrection spell. He believes that it could work, and wants to test it out, but Jalil's father claims that such an important historical artifact cannot be misused. Frustrated that his father does not believe him, Jalil is influenced by Hawk Moth and transforms into "The Pharaoh" with Egyptian god powers who intends to bring back Nefertiti using Alya as a sacrifice. In this episode, there was a long line of Ladybugs going back over 5,000 years with Marinette being the latest Ladybug.

During Career Day in Marinette's class, Chloé loses an expensive bracelet (to Plagg) and accuses Marinette of stealing it, as she had just slipped over Chloé's bag. Chloé persuades her father, Mr. Bourgeois, to order Officer Roger to handcuff Marinette and search her belongings. Roger, however, refuses, saying that he cannot do that, unless there is evidence Marinette stole Chloé's bracelet, as it is against the law. As a result, Mr. Bourgeois, who is the Mayor of Paris, fires Roger. Infuriated at the mayor over this issue, Roger becomes akumatized by Hawk Moth and changes into "Rogercop", a RoboCop-themed villain who wants to bring justice to those who break the law. Not to mention that his police car turns into a futuristic flying car.

Nathaniel Kurtzberg is daydreaming in class of being a superhero who is rescuing his crush, Marinette, from Stormy Weather and Lady Wifi. Soon embarrassed by Chloé for insulting his comic drawings, Nathaniel is influenced by Hawk Moth and becomes the "Evillustrator", a villain whose drawings come to life and also erasing objects in a similar fashion. During this time, Marinette has to put up being paired with Chloé and her only friend, Sabrina, in a science project, while depending on Cat Noir to protect her from Evillustrator. The next day, Marinette nervously says Cat Noir is "awesome" in front of Adrien.

It's Valentine's Day and love is in the air! After reading a love poem thrown away by Adrien, Marinette comes to the conclusion that the poem is about her, making her ecstatic, even though the poem was originally intended for Ladybug. Kim is planning to ask his crush to be his Valentine. Marinette, in her love-sick daze, encourages Kim to go for it. When Kim sees his crush – Chloé – he is humiliated and rejected cruelly. Kim succumbs to Hawk Moth's akuma and turns into "Dark Cupid", an evil winged-being whose arrows can replace true love and friendship with pure hate and mean-spirited. One of his victims is Cat Noir, who is now Ladybug's enemy, just as he was about to confess his love to her.

After finding out Chloé has been blackmailing people from running against her as the class representative, Marinette decides to nominate herself for the position. Wanting to prevent Marinette from winning, Chloé organizes an autograph session by rock musician, Jagged Stone, to bribe her classmates into voting for her. Meanwhile, Armand D'Argencourt, Collège Françoise-Dupont's fencing teacher, has just lost the Paris mayoral elections by a landslide. As the press continues to mock him, Armand is influenced by Hawk Moth and becomes "Darkblade", an armored black knight (according to his heritage), who zaps people, transforming them into an army of armored knights to overthrow Paris.

Alya shows Marinette a video she recorded of Ladybug talking to her, but Marinette accidentally deletes it. Before Alya finds out, Marinette steals her phone and frantically tries to re-create the footage. Meanwhile, Mylène's father, Fred Haprèle, has just picked up his fixed hat from Marinette, and is getting his first premier gesture performance called The Mime's Extraordinary Adventures at the Eiffel Tower. However, his partner, Chris, deliberately makes him late at catching the troupe bus, and convinces their manager Sarah to let Chris take the lead role instead. Disheartened, Fred becomes akumatized by Hawk Moth and turns into "The Mime", a supervillain who can pantomime anything to make it reality, and attempts to seek revenge.

Marinette's great uncle, a world-renowned Chinese chef, Wang Cheng, visits Paris to participate in a cooking show called The Greatest Chef in the World. Adrien comes over to help translate. Before the competition begins, Marinette and Adrien runs into Chloé, who is on the judges' panel. Chloé sabotages Cheng's famous Celestial Soup, causing him to get poor results in front of the judges. Confused and disgraced, Cheng becomes akumatized by Hawk Moth and turns into "Kung Food", a villain who enslaves those who had eaten his ruined soup and plans to cook Chloé in the soup.

Collège Françoise-Dupont is sending two students to represent them at a video game tournament, where they will compete with other schools in a fighting game known as Ultimate Mega Strike III. After Marinette notices Adrien is one of the potential candidates, she participates in the selections in order to be able to team up with Adrien. She manages to defeat another candidate, her classmate, Max, who has been training for a whole year and was looking forward to participating. Upset about all his gaming training gone to waste, Max is persuaded by Hawk Moth and turns into "Gamer", a dark player who uses a pyramid-shaped mecha-like ship, from the Ultimate Mega Strike III game that zaps people and objects, turning them into green "experience point" balls, which upgrades his ship. Ladybug and Cat Noir has to fight him in a similar videogame fashion with the battle between robots.

Nino develops a crush on Marinette so Adrien offers to help him by asking her out to the zoo. Marinette, however, thinks Adrien is asking her out and happily accepts. When at the zoo, Nino and Marinette are the only ones to show up; Adrien and Alya, at the same time, are hiding out in bushes nearby, helping the two talk to each other by instructing them via earpiece. But they end up leading to a comedy of errors, that Nino is actually in love with Alya! Meanwhile, Kim mocks the new black panther in the zoo, claiming to the zookeeper and Alya's father, Otis, that he can run faster than it. Enraged by his remarks, Otis becomes akumatized by Hawk Moth and mutates into "Animan", a villain who can shape-shift into any animal he desires, including extinct species. Afterwards, Nino and Alya find out they share a lot of common things with each other.

Chloé is being harassed by something invisible, and Adrien and Marinette are immediately on the case. After talking with the concierge at the Le Grand Paris hotel, where Chloé lives, they discover Chloé had a fight with Sabrina, and had claimed that Sabrina is no longer her friend. Heartbroken over her words, Sabrina was akumatized by Hawk Moth, turning into the "Vanisher", a completely invisible entity. As Ladybug and Cat Noir fight Vanisher, Chloé wants to join in, donning a fake Ladybug costume. However, this only causes the fight to get more difficult and Ladybug forces Chloé to leave. Only when Chloé has left the scene does Ladybug realize Chloé was right all along about where the akuma is, but despite this, she does not apologize to Chloé. Feeling betrayed by her idol, Chloé also becomes akumatized and changes into "Antibug", a darker, opposite version of Ladybug.

Marinette is babysitting Manon. They are playing with hand-crafted dolls that Marinette made herself, Marinette playing as Ladybug and Cat Noir and Manon playing as Lady Wifi, Rogercop and Evillustrator. Because Marinette always plays as the Ladybug and Cat Noir dolls, Manon laments that Marinette always wins and bursts into tears. Feeling guilty, Marinette allows Manon to borrow her Ladybug doll. However, Nadja Chamack, Manon's mother, doesn't want her to borrow it, as she complains that Manon already has too many toys; they get into a dispute, resulting in the Ladybug doll getting torn. Despite that, Manon still wants to borrow the Ladybug doll, so she asks Marinette for it behind her mother's back. Marinette hesitates and decides on a compromise instead, allowing her to borrow the Lady Wifi doll instead. Chamack notices Manon plays with the doll, and angry that Manon had defied her instructions, she confiscates it from her. Upset, Manon becomes influenced by Hawk Moth and turns into the Puppeteer, a villain who can control the people Marinette's dolls are based on.

At class picture day, Marinette's classmate Juleka is hesitant about participating, as she believes that she is under a curse where any picture she is in will have her face covered. Wanting to be closer to Adrien in the photo, Chloé has her friend Sabrina lock Juleka in the bathroom while she takes her place in the centre of the photo, beside Adrien. Believing that she'll always stay cursed and unnoticed, Juleka becomes influenced by Hawk Moth and turns into Reflekta, a flamboyant villain who can zap people into making them look exactly like her.

Rock musician Jagged Stone has problems with his manager, who wants to change the look of his new album's cover and make him record a duet with XY, a hot new music artist who replaced Stone at the number-one position on the music charts. Although they agree on a compromise on the cover by having Marinette design it, Stone is later offended when he watches a interview given by XY, who claims that technology matters more than music, rock 'n' roll is no longer in style, and that Stone was no match for him. Enraged, Stone becomes influenced by Hawk Moth and turns into Guitar Villain (a reference to the title of "guitar hero" given to legendary guitarists in France[84]), a wild musician with a pet dragon, who influences people into headbanging and dancing uncontrollably by playing his guitar.

Marinette's class is visiting the Grand Paris hotel, as part of an internship programme to try out some of the jobs that the staff do in the hotel on a daily basis, when rock idol Jagged Stone arrives. While Jagged is checking in, an overly-obsessed fan named Vincent Asa sneaks in behind him and tries to take a picture with Stone, but he is swiftly kicked out of the hotel by Jagged's assistant, warned to never approach Stone again. Angry at being shunned by his idol, Vincent becomes influenced by Hawk Moth and turns into Numéric, a supervillain who uses a head-mounted telescopic camera to take photos of people, making them vanish and trapping them in a white empty space by "digitising" them into living portraits that appear on his apartment wall.

Nino is a contestant in a game show called The Challenge, where he has to get Mayor Bourgeois to dance. Despite being invited to see Nino, Marinette is grounded by her parents for missing too many classes at school, not knowing that she had been working as Ladybug. As Nino completes his challenge, the next contestant, a hypnotist named Jacques Grimeau, is given the challenge to hypnotize Adrien's father Gabriel Agreste. However, Gabriel refuses to participate in the challenge, causing Jacques to fail. Angry that he was not given the chance to at least try, Jacques becomes influenced by Hawk Moth and turns into Jackady, an extravagant villain who can hypnotize someone by throwing playing cards at them.

Marinette's classmate Rose is excited about Prince Ali's visit to Paris, but is caught at school spraying perfume on her fan letter and using a cellphone in class. Tikki feels ill, so Marinette plans to take her to a healer, but when Marinette trips on the stairs, Tikki is picked up by Chloe, who plans to give Tikki as a plush toy gift to Prince Ali. Chloe tears up Rose's letter, telling Rose that Prince Ali has no interest in her. Hurt, Rose is influenced by Hawk Moth and becomes Princess Fragrance, a villain whose perfume spray makes people serve her, and who desires to have Prince Ali for herself. The untransformed Marinette must recover Tikki and stop Fragrance from taking over all of Paris.

Adrien discovers a book in his father's safe that details the history of the Miraculouses and steals it to learn more. Later, a new student named Lila arrives who claims to be good friends with Ladybug, a fact Marinette knows is a flat-out lie. In order to win Adrien's affection, she lies again and tells him that she is descended from the Miraculous holder Volpina, whose superpower is the power of illusions. Upon hearing this, Marinette is overcome with jealousy and transforms into Ladybug to call Lila on her lies in front of Adrien. Embarrassed, Lila is influenced by Hawk Moth, who transforms her into Volpina with the hope that she can gain Ladybug and Cat Noir's trust and betray them.

It's Marinette's first day of school. Hawk Moth captures a butterfly kwami named Nooroo and forces his allegiance. Hawk Moth's butterfly brooch allows him to give someone a superpower they desire and to make that person obey his will. He plans on using his new powers for evil purposes, intending to create villains to lure the heroes out to fight them, so he can steal their Miraculouses and gain absolute power. Master Fu, a 186-year-old Chinese man,is notified of Hawk Moth's capture of Nooroo through Wayzz, his own kwami, a turtle. However, he is too old to fight anymore, so he pretends to be a weak old man, travelling Paris to find suitable charges for the Black Cat and Ladybug Miraculouses, hoping they can stop Hawk Moth and free Nooroo. He is helped by Marinette when he crosses a road and is almost hit by a car, and Adrien when he pretends to have fallen down. As school is dismissed, Ivan and Kim, two of Marinette's classmates, have a dispute, after Kim sends Ivan an offensive message on paper. Upset and angry, Ivan becomes Hawk Moth's first ever victim, turning into Stone Heart, a giant rock monster who grows in size after taking damage. Master Fu learns of this, and has no choice but to quickly deploy both the Black Cat and Ladybug Miraculouses, sending them to Adrien and Marinette. Marinette and Adrien both find a small box in their room, and after touching them, are quickly greeted by Tikki and Plagg. Both kwamis give their charges a quick explanation; soon Marinette and Adrien transform into Ladybug and Cat Noir and rush to stop Stone Heart. Despite their lack of experience and poor fighting skills, they manage to defeat Stone Heart and free the akuma. However, Ladybug forgets to purify the akuma after the fight; it flies off, duplicating itself and infecting many people, turning them into immobilised Stone Hearts. The episode ends as Marinette learns of her fatal mistake, and in her despair, thinking that she can't do her job as Ladybug, removes her earrings and puts them away under her dressing table, causing Tikki to disappear.

The next morning, Marinette brings her earrings to school and slips them into Alya's bag, still upset for forgetting to purify the akuma and convinced Alya would be a better Ladybug. Adrien sneaks to school, desperate to leave his house and make friends. Questioned by his classmates, nobody believes Ivan when he claims not to remember anything; he storms off in anger when Chloé mocks him. Marinette comforts Ivan; encouraged by her, Ivan sings Mylène a love song, but accidentally scares her off. Ivan turns into Stone Heart again with Hawk Moth's akuma, and takes control of his duplicates around Paris, which come to life. Stone Heart breaks into the classroom, grabs Chloé and Mylène and runs off, summoning his duplicates. Adrien rushes to stop Stone Heart as Alya takes chase to film the battle; Marinette runs after her, wanting to pass her the earrings. Stone Heart's duplicates catch Cat Noir as he saves Alya from being crushed by a flying car. Marinette has no choice but to transform; breaking Cat Noir out, they rush to Trocadéro. Ladybug catches Chloé when Stone Heart throws her towards Pont d'Iéna from the Eiffel Tower's lower deck. A swarm of akumas fly out of Stone Heart's mouth, forming Hawk Moth's face, who declares that Paris will be spared if Ladybug and Cat Noir's Miraculouses are surrendered. Ladybug refuses, stating that Hawk Moth is the one at wrong, and cleanses the akuma cloud. Hawk Moth orders Stone Heart to take their Miraculouses; he and his duplicates begin to climb the Eiffel Tower. Ladybug climbs to the top of the tower, using her yo-yo to make Mylène kiss Stone Heart's chest; surprised, he drops the paper ball the akuma is in. Ladybug crushes it and cleanses the akuma. After her magic cleans up the damage, Ladybug passes Mylène Ivan's song lyrics. Mylène hugs Ivan; Ladybug and Cat Noir run off to transform back. Later, Adrien's father allows him to go to school while Marinette stands up to Chloé, taking the latter's seat. That evening after school, it's raining outside; Adrien hands Marinette his umbrella, and the two share an intimate moment before parting ways. Master Fu and Wayzz watch from afar, satisfied with their decision to give them the Miraculouses.