This British programmer tells the dark, thrilling tale of a research scientist who resorts to murder to ensure continued funding for his experiments. The killing begins after the slightly insane Dr. Sartorius (Boris Karloff) runs out of money for his experiments with curing paralysis. He is so close to a breakthrough and so desperate for cash that he agrees to kill the wealthy husband of Lady Yvonne Clifford, in exchange for half of her husband's cotton fortune. To do this, he gets hired as Sir Charles Clifford's personal physician and so begins to slowly poison him with injections. Things go awry when the ailing Sir Charles figures out the scam and changes his will to benefit his son from his first marriage. Unfortunately, word gets out and Lady Yvonne changes her deal with Sartorius, claiming that now he must kill the father and the son. But neither the doctor nor the conniving wife count on interference from nurse Eve, who has fallen in love with the son.