Hester ran down the beach, firing her gun at the limpet until its black hull was lost in a boiling of white water. Then there was nothing to do but shout Wren's name ouer and ouer, hoarse, her lonely uoice the only sound remaining as the lap and wash of the Autolycus's wake faded into silence.

Anchorage is no more. The brave ice city that rescued Tom and Hester so long ago is now a static settlement – Anchorage-in-Vineland; a sleepy, hidden secret, full of people who've forgotten hard times, and children who never knew them. Bored children, like Wren Natsworthy, Tom and Hester's daughter. Wren is fifteen, and thinks she's eager for excitement. When the Lost Boys turn up on the beach, searching for the mysterious Tin Book, Wren's sure that her adventure is here for the taking.

But trusting the Lost Boys is a dangerous start to and adventure, and before another day is out, Wren will find herself a captive, and then a slave, and then the bait that leads Tom and Hester back into perilous waters.....