Will, Kevin, Rose, Quentin and Fiona have overcome supercomputer REX and escaped their island prison for the open sea.

Instead of sailing to freedom, suddenly everything changes. Will wakes up on an enormous container ship without knowing how he got there. He explores blood-stained corridors and deserted cargo holds for his friends, and senses he is being watched. Then Will encounters something new in his life: adults. But these are adults beyond Will's darkest nightmares.

Will and his four friends link up with a lone doctor who swears he is on their side, but is he? Who can Will trust and what is really going on? Will & Co. have to work it out fast and survive in the meantime. Because unknown to them all, there is something much worse aboard ship and it's about to emerge . . .