Tell No One by Harlan Coben, paperback novel

For Dr. David Beck, the loss was shattering. And every day for the past eight years, he has relived the horror of what happened. The gleaming lake. The pale moonlight. The piercing screams. The night his wife was taken. The last night he saw her alive. Everyone tells him it’s time to move on, to forget the past once and for all. But for David Beck, there can be no closure. A message has appeared on his computer, a phrase only he and his dead wife know. Suddenly Beck is taunted with the impossible—that somewhere, somehow, his wife is alive . . . and he’s been warned to tell no one.