Matt Cruse works as a cabin boy on the passenger cruise ship Aurora. When pirates attack the ship, he sets off with Kate de Vries on an adventure that takes them to an uncharted island that was once explored by Kate's grandfather.

Based on a children's book by Kenneth Oppel, the film tells the tale of a 15-year-old boy who works on a luxury airship that is part dirigible, part passenger cruise ship. When air pirates attack the airship, the boy, along with a female partner, embark on an adventure that includes strange flying creatures, secret lairs, nasty villains and uncharted volcanic islands. Matt Cruse is a cabin boy on the Aurora, a huge airship that sails hundreds of feet above the ocean, ferrying wealthy passengers from city to city. It is the life Matt's always wanted; convinced he's lighter than air, he imagines himself as buoyant as the hydrium gas that powers his ship. One night he meets a dying balloonist who speaks of beautiful creatures drifting through the skies. It is only after Matt meets the balloonist's granddaughter that he realizes that the man's ravings may, in fact, have been true, and that the creatures are completely real and utterly mysterious.

Matt Cruse is the cabin boy of the Aurora, the 900-foot luxury airship he has called home for the past two years. While crossing the Pacificus, Matt fearlessly rescues the unconscious pilot of a crippled hot air balloon. Before he dies, the balloonist tells him about the fantastic, impossible creatures he has seen flying through the clouds. Matt dismisses the story as the ravings of a dying man, but when Kate de Vries arrives on the Aurora a year later, determined to prove the story is true, Matt finds himself caught up in her quest. Then one night, over the middle of the ocean, deadly air pirates board the Aurora. Far from any hope of rescue, Kate and Matt are flung into adventures beyond all imagining...