Dr. Victor Sartorius, a dedicated but dying medical researcher working in Morocco, becomes frustrated when his funding is cut off and his experiments ended. He is approached by Lady Yvonne Clifford, the young and beautiful wife of wealthy but aging aristocrat Sir Charles Clifford. She has been carrying on an affair with a gold-digging army captain and offers Sartorius the 20,000 pounds he needs to continue his research if he will become her husband's personal physician and covertly murder him. When Sir Charles' son Roger enters the picture, it is clear that he is marked for death too. Only Sartorius' altruistic nurse Joan stands in the way.