A 28-year-old man seems the picture of health, until he fractures his leg while skating in New York's Central Park. Within twenty-four hours of his surgical treatment he is dead.

Next, a 36-year-old mother has knee surgery to repair a torn ligament in her knee - and within twenty-four hours she too has died.

Confronted with the puzzling deaths of young, healthy patients after routine treatment, medical examiners Dr Laurie Montgomery and Dr Jack Stapleton begin to investigate.

Up against resistance from her superiors, and coping with a personal life that continues to fragment, Laurie's need for answers becomes even more urgent. Could all these deaths be intentional? With time winding down, she and Jack embark on a race to connect the dots.