Injured scientist Eric Godfrey asks his protege to give him a fatal dose of opiates to end his misery. When he dies the doctor is accused of murder.

After his graduation from medical school, Michael Forbes accepts a position as the assistant to the renowned Dr. Eric Godfrey at the Jefferson Institute of Medical and Allied Sciences in New York. Michael works day and night for six months researching spondylitis-deformans, a disease which causes rigidity of the spinal column. After Michael meets Dr. Godfrey's young and attractive wife Ellen, Dr. Godfrey encourages Michael and Ellen to use his opera tickets because he won't be in town for the performance. On the way to the opera house, Ellen's chauffeur has an accident outside a small Italian restaurant run by friendly Italian immigrants Luigi and his wife, who offer Michael and Ellen pizza. After hearing Luigi sing opera as he prepares the pizza, Michael and Ellen give Luigi and his wife their tickets and remain at the restaurant talking. Over the next few weeks, Luigi and his wife go to many operas, as Michael and Ellen spend evenings together at the restaurant, while Dr. Godfrey is away at an excavation site in Arizona investigating a cave where a fossil showing evidence of spondylitis-deformans has been found. When Ellen receives a telegram that her husband is returning the next day, she and Michael realize that they have fallen in love. Michael wants to leave town, but Ellen convinces him that they haven't done anything wrong. As they say goodbye to each other at the Godfrey home, Dr. Godfrey's assistant, the cold and exacting Dr. Anna Burkhart, arrives and tells Ellen that Dr. Godfrey has fallen from a ledge in the cave and injured his spine. Ellen, Michael and Anna fly to Arizona with Dr. Creighton, a specialist. They find Dr. Godfrey paralyzed in the cave, and Dr. Creighton says that because his spine is crushed, he will die and will suffer greatly until his death. Unable to bear the pain, Dr. Godfrey pleads with Michael and Anna to give him an overdose of the opiates used to kill the pain, but they both refuse. One night, as Dr. Godfrey taunts Michael and begs him for an overdose, Michael becomes tormented by imaginary voices and visions. Shortly thereafter, he reports to Ellen, Anna and Dr. Creighton that Dr. Godfrey has died. Anna demands an autopsy and accuses Michael of murder. Michael admits to the "mercy killing," and after he is indicted, one of New York's finest criminal lawyers, James Bernard, offers to defend him for free. The news of the mercy killing brings crowds of curiosity-seekers, who swarm around the cavern. Dr. Creighton, on the witness stand, notes that the medical profession is against mercy killings because of the danger of putting so much power into the hands of an individual who could be wrong about a diagnosis or act from selfish or criminal motives. He also comments that cures for seemingly incurable conditions are sometimes found. After Luigi, who is called as a surprise witness, reveals Michael and Ellen's meetings at his restaurant, Anna testifies that while Dr. Godfrey was away, she always reached Michael at the Godfrey residence when she called at night. Ellen interrupts and confesses that Michael loved her and that she loved him, but she insists that she loved her husband more and that Michael sacrificed everything to ease her husband's pain. Michael then admits that he previously confessed to the mercy killing to keep Ellen's name out of the papers and to keep Dr. Godfrey's reputation from becoming besmirched by scandal. He now states that he did not kill Dr. Godfrey. After he reveals to Bernard that he left for Dr. Godfrey, the night before he died, an extra grain of the pain killer, which, he insists, could not have killed him, Bernard surmises that Anna and their cohort Dr. Empey did the same thing, and that Dr. Godfrey swallowed the extra three grains and killed himself. Satisfied with this explanation, the judge instructs the jury to find Michael not guilty, which they do.