Marinette's class is having a field trip to London, but Marinette believes she cannot attend since doing so would leave Paris vulnerable to Hawk Moth. Master Fu gives her the Horse Miraculous, which grants the power of teleportation, so she can enjoy herself and be able to return to Paris in case of an emergency. Max's mother, a train conductor who directs the Startrain, dreams of being an astronaut and has taken an exam to begin training. However, a rogue akuma gets aboard the train to London in Sabrina's big suitcase after a botched attempt to akumatize Officer Roger. When Max's mother succumbs to nerves waiting for confirmation about whether she passed, the akuma infects her and turns her into "Startrain" itself, and she drives the train into outer space. Since the akuma is outside of Hawk Moth's range of influence, Gabriel is forced to rely on the heroes to rescue Adrien. Ladybug gives Max the Horse Miraculous, turning him into the superhero "Pegasus". With his aid, the heroes teleport the train back to Earth, so Ladybug can safely purify the akuma. Afterwards, Max's mother gets the e-mail confirming she passed her exam, much to her delight.

When Tikki tries to stop Plagg from eating a piece of cheese in the classroom, Ms. Mendeleiev, Collège Françoise-Dupont's physics teacher, catches them, but they escape. Ms. Mendeleiev tries to prove the existence of the magical creatures on a TV show, but the viewers are not convinced by her theory. Marinette and Adrien become convinced that their partner must be one of their fellow students, and Adrien even specifically suspects Marinette; conversation reveals that they must give up their Miraculouses if their identities are compromised, even to each other. Angry that no one believes her theories, Ms. Mendeleiev gets akumatized into "Kwamibuster", a Ghostbusters-themed villain with a vacuum to capture kwamis. Both superheroes lose their kwamis to Kwamibuster, so Adrien hides in a costume, and Marinette flees to Master Fu. She borrows many other Miraculouses despite the physical risk, and has Mullo of the Mouse Miraculous transform her into "Multimouse", giving her the power to divide herself into miniature clones. Some of her clones also use "unify" to undergo alternate transformations and employ the various kwamis to best Kwamibuster, freeing all the captured kwamis. Multimouse then uses the Fox Miraculous to make it appear that Marinette and Ladybug are two different people to erase any idea from Cat Noir of them being the same person. Cat Noir apologizes to Ladybug for his kwami being at "that elementary school" (to convince her that he is not a student there) and discourages Ms. Mendeleiev from making any more attempts to prove the kwamis are real. Marinette returns all of the extra Miraculouses to Master Fu. He remarks how exceptionally strong Marinette is to have used so many at once.

Since becoming the new guardian of the Miracle Box, Marinette has been overwhelmed. She doesn't see her friends anymore, abandons Cat Noir, and misses all her dates with Luka. Luka senses that Marinette has a secret, but she can't tell him that when she leaves, it is to become Ladybug and save Paris. Deeply hurt that Marinette doesn't trust him enough to confide her secret, Luka is akumatized into Truth. Helped by his sentimonster, Pharo, a giant eye capable of immobilizing people so that way Truth can hit people with his beam to tell the truth, he not only wants to know Marinette's secret but also Ladybug and Cat Noir's secret for Shadow Moth.

In 'Lies', Kagami thinks that Adrien doesn't love her, and because he's also Cat Noir, he always has to lie to leave her so he can save Paris. Then Kagami finds the lucky charm Marinette gave Adrien, which just adds fuel to her anger.

Ladybug and Cat Noir face someone they know well - and of whom they never thought that one day they would have to fight against him.

Marinette meets Zoé, a new student at her school. But she has no idea that Zoé is the half-sister of someone very powerful at school and that that person will do anything to make this friendship be crushed.

When Chloé is akumatized into Queen Banana, Ladybug decides to entrust a Miraculous to a new and promising ally. She should help her to stop the supervillain and her giant gorilla.

Marc, Nathaniel, Alya, Zoe, Rose, Juleka, Mylene, and Alix try to help Marinette get closer to Adrien, but Chloe has filmed the incident on video and she plans on showing the video to Gabriel at his gala. Marinette disguises herself as a waiter so she can erase the video from Chloe's phone and prevent Adrien from getting homeschooled. Chloe is forced to relinquish her phone, but she secretly grabs her SIM card. Gabriel confronts Felix for taking his wedding ring from him and he gives his uncle a fake ring. Shadow Moth creates a sentimonster of himself. "Gabriel" threatens to get rid of Felix for his thievery, making him vulnerable to akumatization, but he is able to resist Shadow Moth's influence and Felix makes his escape. Shadow Moth akumatizes his sentimonster instead. Chloe steals Bob Roth's phone so she can show her video to "Gabriel". However, Chloe and Bob get captured by "The Collector" on his tablet and he soon begins to imprison everyone else on his tablet. Ladybug and Cat Noir manage to get Felix to safety. The two heroes are able to defeat "The Collector", Ladybug unknowingly gives "Gabriel" a magical charm. Chloe tries to show her video to "Gabriel" again, but Bob Roth gets his phone back and he erases the video, leaving Chloe humiliated and dismayed that her plan has failed. However, Felix begins to realize that his uncle is a supervillain. Marinette goes home and her friends come up with a comic book idea based on her adventures as a waiter. In a post-credit scene, Gabriel puts two fake miraculouses in his safe in order to lure his nephew into a trap.

When Marinette and her friends go to protest against the deforestation of a square in Paris, Mayor André Bourgeois is enraged and is akumatized. Now Ladybug will have to defend not only the square, but all of Paris.

What would happen if Ladybug and Cat Noir discovered their secret identities? To beat a villain, Ladybug calls on nine superheroes when all she needed was Cat Noir and his cataclysm. What will Ladybug do?

Ladybug manages to assemble an amazing team of superheroes now that she is Guardian of the Miraculous, but Cat Noir is feeling left out and decides to give up his miraculous. Ladybug now needs to deliver the Cat Miraculous to someone else.

When one of Shadow Moth's favorite victims is akumatized into Penalteam, a fearsome team of supervillains, Ladybug calls on her own superhero team in order to face her; may the best team win.

Shadow Moth's trap closes in on Ladybug and Cat Noir, threatening to turn their fate upside down.

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.

Marinette decides on giving up her love of Adrien to avoid any more disasters and focus on preparing to battle Monarch, but the days go by and no akumatized villains have appeared yet. Has Monarch given up?

What if Monarch could force the Kwamis who know Ladybug's address to lead him to her? The unfortunate little creatures would have no choice but to obey him... And if Monarch showed up at Marinette Dupain-Cheng's home, would she be able to escape him?

While Marinette tries to convince herself that she has to stop being in love with Adrien because it diverts her from her superhero role, she discovers that she has feelings for someone else.

Marinette tries to convince herself that she loves Chat Noir to forget about Adrien. Adrien has given up on being in love with Ladybug, is trying to declare his feelings to Marinette.

Marinette uses Tikki's Reunion to summon Johanne of Arc, a previous Ladybug holder, to ask about the possible romance between her and Chat Noir. Meanwhile, Pharaoh is reakumatized and asks questions for Ladybug to solve.

Despite Alya's protests, Marinette decides to pursue her new love for Cat Noir by going on a romantic night out with him. But they are spoiled after encountering a Ladynoir fan who reveals some unsettling revelations about their love lives

Tikki and Plagg are sad to see their carriers so sad to be forced to give up their feelings. The Kwamis will then make a radical choice that will change many things in Paris.

Monarch is faced with a unique opportunity that he refuses to lose. The Kwamis made a decision that completely distracted Marinette and Adrien from their responsibilities. For better and for worse.

Marinette's friends decides to help her to get closer to Adrien, then the whole gang finds out that one should always be clear with friends.

Luka develops a special interest in Bob Roth, who would do anything to make money. Luka himself would do anything to defend his values and his friends.

Marinette starts to feel traumatized when she and Adrien prepare to have a normal date at the pool as she once had a crush on Kim last year and Chloe pulled a series of nasty pranks on her.

Monarch is ready to do anything when he senses a unique occasion to get a real second chance even if it is his last chance to seize the Miraculous.

As the gang comes up with yet another overcomplicated plan to bring Marinette and Adrien together, Lila uses her talent for manipulation to persuade Kagami that Marinette is a liar who abuses everyone else's kindness. Shocked, Kagami is akumatized into Riposte Prime. She lays into Marinette at the very moment when Adrien had managed to finally make her feel comfortable around him. Will Lila's poisonous lie ruin the friendship between Kagami, Marinette and Adrien?

When Marinette and Zoe are chosen to organize the end-of-school-year party, Marinette learns that Zoe is secretly in love with someone in ninth grade at school. Zoe says that she cannot talk about it. To Marinette, this can only mean one thing: Zoe is in love with Adrien! But before she finds out whether she is right or not, a common enemy of the girls will try to ruin their beautiful friendship

Adrien must attend a dance organized by his father and Mrs. Tsurugi. He will be the King of the Ball alongside Kagami, who has been chosen to be this year's Queen. But neither of them wish to go for the dance.

Marinette decides to have a heart-to-heart with the father of the boy she loves. By seeing her courage her friend Kagami finally dares talk to her mother.

Lila uses an incident in class to calls for new elections to replace Marinette as class representative.

Junior high will soon be over, Lila and Chloe are planning to defend their classmates' future before their teachers; Marinette and Adrien worries what the two brats' next evil plan will be.

The end of school year is nearing, and rebellion is brewing. Monarch decides to on a plan that is dangerous for his secret identity and for Ladybug and Cat Noir, too.

Chloe and Monarch are more powerful than ever, Ladybug and Cat Noir wonder about their powers. Marinette and Adrien's lives are about to change forever.

Adrien disobeys father to go find Marinette but she discovers a secret nothing could have prepared her for.

Monarch places the final pieces of his villainous plan on his chessboard of evil.

Monarch's ultimate plan is in motion. Nothing seems able to stop him now. Especially considering that, while the world descends into chaos, the supervillain has just trapped Ladybug in person...

When Marinette and her friends go to protest against the deforestation of a square in Paris, Mayor André Bourgeois is enraged and is akumatized. Now Ladybug will have to defend not only the square, but all of Paris.

Marinette's class is having a field trip to London, but Marinette believes she cannot attend since doing so would leave Paris vulnerable to Hawk Moth. Master Fu gives her the Horse Miraculous, which grants the power of teleportation, so she can enjoy herself and be able to return to Paris in case of an emergency. Max's mother, a train conductor who directs the Startrain, dreams of being an astronaut and has taken an exam to begin training. However, a rogue akuma gets aboard the train to London in Sabrina's big suitcase after a botched attempt to akumatize Officer Roger. When Max's mother succumbs to nerves waiting for confirmation about whether she passed, the akuma infects her and turns her into "Startrain" itself, and she drives the train into outer space. Since the akuma is outside of Hawk Moth's range of influence, Gabriel is forced to rely on the heroes to rescue Adrien. Ladybug gives Max the Horse Miraculous, turning him into the superhero "Pegasus". With his aid, the heroes teleport the train back to Earth, so Ladybug can safely purify the akuma. Afterwards, Max's mother gets the e-mail confirming she passed her exam, much to her delight.

Ladybug and Cat Noir face someone they know well - and of whom they never thought that one day they would have to fight against him.