In the Pennsylvania court of Calvin Cooke, a rigid "letter-of-the-law" judge, attorney David Douglas loses a murder trial when he fails to prove that the accused's state-of-mind is critical in determining guilt. Unknown to Calvin, David, whom the judge dislikes because of his liberal interpretation of the law, is dating his daughter Ellie. Later that day, Ellie complains to her mother Catherine, who is preparing for her twentieth anniversary dinner, about her father's obdurate nature. That evening, Cathy experiences a severe wave of pain and dizziness which she conceals from Calvin and Ellie. Before dinner, however, she manuevers to be alone with longtime friend and family physician, Walter Morrison. Upon describing her symptoms to him, Walter asks her to come to his Philadelphia office the following day. Cathy keeps the appointment secret from Calvin and Ellie and the next day is subjected to a battery of tests. Although Walter is optimistic with Cathy, as soon as she leaves, he arranges for the test results to be submitted to several specialists around the country. In court the next day, Calvin gets an urgent message from Walter, who later tells him that Cathy is suffering from a fatal illness that will develop rapidly and with great pain. The only help Walter can offer are pain relief pills that are highly toxic. He recommends that Calvin keep the information from Cathy and try to make her remaining time as pleasant as possible. Unwilling to confide in Ellie, Calvin decides to take Cathy on a second honeymoon trip, during which the two happily if briefly re-experience their early days together. While in an amusement park house of mirrors, however, Cathy is stricken by a violent headache, blurry vision and dizziness and pleads to return to the hotel, where she continues experiencing great pain. Calvin gives her the prescribed amount of the pain reliever, telling her it is aspirin, but Cathy passes most of the night in excrutiating agony. Calvin fleetingly contemplates giving her more medicine, but reconsiders. The following morning Cathy awakens to find a note from Calvin saying that he has gone for the newspaper and while searching for more aspirin, comes across Walter's pain medicine prescription and diagnosis. Meanwhile, Calvin has telephoned Walter, distraught over Cathy's suffering and talks of suicide and relieving her torment. When he returns to the hotel, Cathy says nothing about discovering the prescription and asks to return home to Ellie. On the drive back in the midst of a rainstorm, the car develops engine trouble and Calvin is forced to pull into a roadside garage and café. While Calvin helps the mechanic, Cathy, sitting in the café, realizes her condition is worsening and calls Ellie. On the road again with Cathy dozing beside him, Calvin is overwrought and intentionally drives the car over an embankment, killing Cathy. Some time later, after he has recovered from the crash, Calvin goes to the district attorney and turns himself in as Cathy's murderer. Despite Ellie's pleas, Calvin refuses to defend himself, believing his motives in no way justify his actions. During the trial, David asks to be appointed to the defense at Ellie's urging, and insists Calvin be found not guilty due to the extenuating circumstances of Cathy's illness. When premeditation and mental instability are suggested, David asks for an autopsy to confirm whether Cathy may have died before the crash. Calvin, meanwhile, experiences doubt about whether his actions were as selfless as he intended. The autopsy proves Cathy died from an overdose of the pain pills which she had filled at the hotel and taken at the café without Calvin's knowledge. Calvin is found not guilty but realizes he remains morally guilty and that the reverse holds true, that a man may be be guilty in deed, but morally innocent.