Boston District Attorney Will Sullivan dreams of becoming the next great governor of Massachusetts. He has a beautiful wife, Joanna, an adorable daughter, Sydney, and a name that the citizens of Massachusetts respect. But Will's plans are shattered the night Joanna discovers a malignant tumor growing in Sydney's stomach. At that devastating moment, both parents resolve to do anything to save their daughter's life.

But in the twilight world of Briarwood Medical Center, nothing is as it seems. Patients on the brink of death are not only surviving, but thriving, while others are withering away. The more time Will spends in the labyrinthine hospital, the more he fears he's losing his grip on reality. When a mysterious, charismatic counselor appears and starts talking to Joanna, she grows more and more distant, until she hardly resembles the woman that Will married. Yet suddenly, miraculously, Sydney is improving.

As winter closes in around the hospital and his dark suspicions build, Will must gather the strength to confront the evil at hand before he loses his family, his political aspirations, his sanity, and possibly his life.