Robert wakes up naked and alone in a thick jungle. The last thing he remembers is being in a plane with his family, but there is no sign of a crash or survivors. Then he discovers the shocking truth—he is in the park near his house, but his familiar world has been transformed into an alien landscape. When he finds others in the same position, he enlists their help in getting back home. But the journey is more perilous than Robert could ever imagine.

Robert is determined to rescue Lorn, who remains trapped in the tiny underground world from which he has managed to escape. She'll die if he doesn't help her. But Lorn doesn't know what danger she is in. Something is drawing her to the dark tunnels underneath her world. Is it something that is calling her home or something more sinister? Can Robert get to her before whatever lurks in the black room does? BLGillian Cross is one of the UK's top children's authors, and has won a host of major prizes, including the Carnegie Medal, the Whitbread Award and the Smarties Prize.

The thrilling conclusion of a groundbreaking trilogy has arrived. Robert journeyed through a strange parallel world with the help of a tiny band of fellow survivors. Now home, Robert, with his best friend, Tom, and sister, Emma, are desperate to save the others before winter sets in and cold destroys their fragile existence. But the three friends discover a sinister connection between their own and the parallel world—a darkness that will test their courage, their friendship, and their hope for the future. Seamlessly blending fantasy with a hard-hitting tale of love and survival, Gillian Cross weaves the final tale in a startlingly original, spellbinding series.