Kat MacKenzie knows something is terribly wrong at the Diablo Beach Nuclear Power Plant, but she can't figure out if it's computer error, equipment malfunction, or human sabotage. Unfortunately, the only person she can trust with the problem is the man she left at the altar two years ago. If Dillon doesn't already hate her, he surely will once he discovers why she abandoned him. The last person he expects to call him is the woman who broke his heart. But FBI Special Agent Dillon O'Malley can't ignore Kat's plea for help-not when national security may be at stake. As enemies become clear and catastrophe threatens, can Kat and Dillon put the past behind them to save the day and secure their future?