Emma Agreste thought she had the perfect life...until she saw her mother kiss the superhero Chat Noir. With the help of her twin brother, Hugo, Emma is determined to stop Chat Noir from ruining their family and stealing away their mother. Meanwhile, Adrien is convinced his children hate him.

Chat Noir is head-over-heels in love with Ladybug, but she is unable to return his feelings. Not understanding the reason why, Chat is left heartbroken. When an Akuma battle causes him to lose his memories—along with other charming aspects of his personality—Ladybug is at a loss. With Chat not himself she starts to realize she may have lost more than she thought.

When Hawkmoth was defeated, Ladybug's cure fixed the broken bridges and burning buildings. But the ground was still tinted red, and the scars in Paris's heart ran deeper than the surface.

Something goes wrong during their holiday and Finland and Iceland end up back to viking times. Armed only with a silly history book and DIY bow without any arrows they go on to find the viking version of Norway and get back to their own time. But the rather big cultural shocks are not the only problem because it might be that the Scandinavians were not exactly the nice guys.

Pissed off at Alya one very early morning, Marinette misdial her best friend's number and ends up telling off an unsuspecting and anonymous Adrien. The pair grows closer through texting as they also reunite years after graduating through work. Marinette has to face her painful past in order to move forward with her heart, but luckily Adrien might be the one able to help her heal.