Lilly is a ten-year-old worrywart. To keep her concerns at bay, she diligently and fervently lists them in a worry book. Her globe-trotting scientist-parents don’t worry about anything. When they learn of a rare sighting of the frangipani fruit fly, they set sail for the fabled Shipwreck Islands. Since water is her greatest fear, Lilly stays behind with her eccentric, librarian great-uncle.

Then news comes that the scientists are shipwrecked, and Lilly must overcome her fear of the sea, find the hidden island, and outsmart a bunch of treasure-hungry pirates to save her parents.