Journalist Harry Fitzglen is less than thrilled to write up the opening of some glittering new art gallery. But the boredom falls away when he meets Simone Anderson, whose oddly compelling photographs are on display. Harry loves a girl with a past, and Simone's is a doozy: What exactly happened to her long-disappeared twin sister? And what is her connection to another pair of twins, born nearly 100 years ago? Every question points to the Welsh border and a ruined mansion called Mortmain House. As Harry delves into Mortmain's grim history, he finds himself drawn into a set of interlocking mysteries, each more curious - and disturbing - than the last.