A mysterious illness claims three lives, and Dr. Alexandra Gladstone suspects an epidemic. She is able to save the fourth, but he's found murdered with his heart surgically removed. Constable Snow is at a loss to find the killer and to keep the village from descending into panic. Alexandra's search for the truth takes her to London for a meeting with renowned doctors and with the intrepid nurse Florence Nightingale. Meanwhile, time is running out, and the killer is still at large. It may already be too late to save the ones she loves.