Twelve-year-old Violet Parma comes into the Grand Nautilus Hotel in the town of Eerie-on-Sea and meets the same-aged Herbert Lemon who works at the hotel and is in charge of lost and found items. Violet asks Herbert to help find her parents who disappeared when she was an infant. The two then learn that the disappearance is related to a local myth of a Malamander--part-fish, part-human monster whose egg is said to make dreams come true--and soon, entities both good and nefarious are hunting the Malamander and the children.