In 1977, Innes Haldane was one of seven extremely dysfunctional teenagers incarcerated in the Unit, an avant-garde psychiatric hospital on the outskirts of Edinburgh. There, she and her fellow inmates were forced into each other's lives, exposed to each other's pasts, and now share a collective memory. Since then, they have spent their adult lives trying to forget the unspeakable acts that sent them there and the terrible secret that occurred behind its walls . until a message on Innes's answering machine with a voice from the past interrupts the quiet life she has tried so hard to make for herself. There is a murderer stalking the former inmates, and the only way for them to save themselves is by reuniting -- no matter what the emotional cost. If the killer doesn't shatter their new lives, the memories being brought back to light just might. Now Innes must contact the others before someone else finds them first.