Reckless Whisper by Barbara Freethy

FBI Special Agent Bree Adams has a personal secret, something she has managed to keep hidden for the past ten years-at least she always thought so… But a chance encounter on a train, and whispered words of chilling consequence change everything. Is the truth about to come out or is someone playing with her mind and her life? Nathan Bishop knew Bree when she was a street kid like him. Their dark past once put him in her debt, and he had to pay up.

The last thing he wants to do is help her again. He has a new life now-a life he could lose with one wrong move. But the beautiful Bree is desperate-how can he walk away? To get to the truth, protect innocent lives and their own, they’ll have to fight their way through the past, as danger stalks their every move, and heartbreaking choices must be made.