It's been several years since Ren of the Undivided and his half-Faerie companion Trása stumbled into to the reality where the Faerie are all but eradicated by the Matrachai. With the help of Pete and Logan Doherty, the human twins stranded with them, Ren must find a way back to save his twin brother, Darragh, from a fate worse than death. Even worse, the Matrachai have their own plans that threaten every magical race in existence. Only the Undivided hold the key to stopping them, and even the Faerie Brethren have turned to Ren for help. But the cost may prove too high, because Ren's nightmares have returned and the closer he comes to saving Darragh and stopping the Matrachai, the more likely the nightmare that has haunted him since childhood - the nightmare where he murders two innocent children - will come to pass.