On rotation at Pittsburgh 's Angels of Mercy Hospital and struggling to finish medical school, Amanda Mason can't afford to make any mistakes—or to reveal a troubling secret. Mysterious symptoms that defy diagnosis have been affecting her performance, and as she struggles to keep control, the only person who seems to notice is the irritatingly observant and sexy Dr. Lucas Stone.

But when one patient showing the same strange symptoms dies and another slips into a coma, Amanda realizes the clock is ticking on her own survival. With the help of her friends— Gina, a roommate recovering from her own trauma; Lydia, a streetwise ER attending; and Nora, a by-the-book charge nurse—Amanda must solve this medical mystery before she becomes the next victim...