One night of passion leaves Belle Brennan longing for her Mr. Mysterious… An undercover operative, Cain Dempsey, leaves the woman he loves in order to protect her. A case he's working on takes a turn for the worst leaving him no choice but to return to her for aide. Belle is the one person he can trust, even if she has every right to be angry with him. Taking an impromptu vacation at her family's lake house Belle is surprised to find Cain at the back door. He's injured, surly, and every bit as gorgeous as she remembers. Lucky for him she's a doctor and doesn't hold a grudge. Can they survive the threats surrounding them long enough to rekindle their growing passion or will Cain's dangerous life destroy them forever?