In a world hit by a wave of mutations transforming humans into animals, François does everything he can to save his wife. As some of the creatures disappear into a nearby forest, he and their son Émile embark on a quest that will change their lives forever.

Mrs. Géquil is an eccentric teacher despised by her colleagues and students. On a stormy night, she is struck by lightning and faints. When she wakes up, she feels different. Will she now be able to keep the powerful and dangerous Mrs. Hyde contained?