Alistair Cleary is the kid who everyone trusts. Fiona Loomis is not the typical girl next door. Alistair hasn't really thought of her since they were little kids until she shows up at his doorstep with a proposition: she wants him to write her biography. What begins as an odd vanity project gradually turns into a frightening glimpse into the mind of a potentially troubled girl. Fiona says that in her basement, there's a portal that leads to a magical world where a creature called the Riverman is stealing the souls of children. And Fiona's soul could be next. If Fiona really believes...

Twelve-year-old Alistair Cleary has washed up on shore. But where? It seems to be Aquavania, the magical realm where children create entire worlds from their imagination. There's something wrong, though. The creators have disappeared and the worlds are falling apart. All Alistair wants is to find his friend Fiona Loomis and go home. Easier said than done. Animals made of starlight, a megalomaniacal boy king, and astronauts who peddle riddles are hard enough to outwit, but they're only the beginning. To find Fiona, Alistair must travel from world to world. He must confront the mistakes of...