Cat lives in Los Angeles, far from the gothic house in Edinburgh where she and her twin sister El grew up, and where they invented Mirrorland, a dark, imaginary place under the pantry stairs, full of pirates, witches, and clowns. Cat rarely thinks about that time any more, or how her estranged sister now lives there with her husband Ross. But when El disappears, Cat is forced to return to the imposing old house. Nothing has changed, and Cat stumbles upon long-held secrets and forgotten ghosts of the past, because someone has left Cat clues on a trail that leads back to Mirrorland—where the truth lies waiting.

"I loved Mirrorland. It's dark and devious, a neo-gothic featuring twin sisters and a deeply frightening old dark house. Beautifully written and plotted with a watchmaker's precision."—Stephen King