Herbert Lemon, Lost-and-Founder at the Grand Nautilus Hotel, knows that returning lost things to their rightful owners is not easy – especially when the lost thing is not a thing at all, but a girl. No one knows what happened to Violet Parma’s parents twelve years ago, and when she engages Herbie to help her find them, the pair discover that their disappearance might have something to do with the legendary sea-monster, the Malamander.