In an Edinburgh hospital a young doctor dies in agony, trapped in a steam filled sterilizer. Three subsequent victims inexplicably bleed to death: lab technician Susan Daniels, little Timmy Watson who was recovering from his 'life saving' operation, and an orderly who cut herself on a broken vase. All three are found to have a powerful anticoagelant introduced into their blood. What madman is at work in the hospital and why? Biochemist Tom Fenton begins his own investigations after stumbling on some of the young doctor's mysterious research. And when his girlfriend Jenny is accused of murder he is even more determined to find the answers - putting his own life at great risk.