Back in Miami after a relaxing honeymoon, Helen Hawthorne and her new hubby Phil are opening their own PI agency—specializing in families with private problems. But even with a new business, Helen can't seem to get away from those dead-end jobs.

Helen and Phil's very first client is Shelby, a woman who wants them to spy on her husband, Bryan. Six months ago, he bought a gym membership—and now Shelby suspects he's developing a killer body for another woman. Suddenly Helen finds herself back in a dead-end job at Fantastic Fitness, working as a receptionist to keep track of Bryan. The only catch is that to work at the gym, Helen has to stay fit and pump some iron herself.

To make matters worse, when their budding agency takes on another case involving a decades-old murder, Helen has to move her workouts to the wee hours of the morning just to keep up. With so much weight on her aching shoulders, will Helen catch a killer and get a body to die for—or just drop dead from exhaustion?