Matt Cruse is cabin boy aboard the Aurora, an airship which truly is lighter than air. Since the discovery of hydrium, a gas that renders even the heaviest vehicle as light as a feather, airships travel all over the world in the same way as planes do today. Matt himself was born on an airship and it is there that he feels most at home.

Matt has high hopes for promotion to junior sailmaker on this voyage - until Kate de Vries, one of the wealthy passengers, arrives on the scene. She's feisty and brave, and won't let social distinctions get in the way of her friendship with Matt. And all their bravery is required when one night, in the middle of the ocean, they are boarded by pirates and caught up in adventures beyond all imagining ...