Dean Koontz's compelling and high-concept new thriller is the story of a young man who owes his life to a heart transplant ... but confronts an imminent and far worse death because of whose heart it was.

At 34, Ryan Perry never expected to find himself on a waiting list for a heart transplant, with time running out.

So when miraculously he receives a new heart and the transplant is a success, he thinks his troubles are over. A year later, he has never felt so good.

But then he starts to get mysterious gifts from an unknown person. He has the feeling he is being watched. $100,000 suddenly vanishes from his bank account, donated to the cardiology department of the local hospital.

And then comes a terrifying threat: everything he has - his money, his reputation, his friends, his freedom, and his new heart - will all be ripped away from him. He is promised a nightmare death.

In grave danger, alone with his beating heart and its secrets, can Ryan unlock the mystery of the enemy who threatens his very existence?

Prepare for the unexpected in this compelling and fast-paced thriller from the master of suspense.