Innes, sensing a connection between the deaths, investigate the mystery of why her co-patients at the Unit are dying. The narrative goes back and forth between the present and 1977. There is also a narrative that is chronologically behind the "main character's" point of view.
Naturally, the kids are hiding a secret, a dark, huge and stomach clenching secret. Innes is actually the most out of the loop out of all of the former former patients. I guess this was necessary to make her not guilty of what the others did, but it was weird to have a main character not really have anything to do with the happenings, except that she knew the people.
The book is suspenseful and fast moving and fairly unpredictable. There were some twists that I did not anticipate. It attempted to flesh out normally "evil" characters, like the former teen sex offender, which I almost felt sympathy for. However, the secret was truly horrible, made me queasy, and totally erased all the sympathy I might have had for the characters involved.