Both a prequel and a sequel to Sharp North (2006), this multiple-time-period dystopia can stand on its own for readers willing to accept some confusion until the world of the novel emerges. As both parallel stories offer high suspense, readers may be willing to wait for that clarity. In 2023, Dom, abandoned in his private school after sudden climate change plunged Britain into perpetual winter, copes with the military unit that has imprisoned him there. Centuries later, Adeline embarks on her own journey to free Britain from a vicious dictator, entering a TV survival game show in order to reach the public. But just who is Adeline, and who are the others living in a future Britain that is drowning under rising seas? Cave crafts a highly imaginative world populated with intriguing and unusual characters. If the solution to his dilemma relies upon an abrupt about-face on the part of two of the characters, the author manages to make their changes of heart plausible. Constantly gripping, always fascinating and completely compelling. (Science fiction. YA)