In the winter of 1868, Eben Frost (William Demarest) goes to a Boston pawnshop and redeems a silver medal, inscribed to "Dr. W.T.G. Morton, the Benefactor of Mankind, with the Gratitude of Humanity." Frost drives to a country farmhouse and gives the medal to Morton's widow, Elizabeth Morton (Betty Field) who explains to her daughter, Betty (Donivee Lee), that Frost was the first person given anesthesia by her father, Boston dentist Dr. W.T.G. Morton (Joel McCrea.) The story flashes back 20 years to find Morton being wildly acclaimed by medical students as the man whose discovery of "letheon" had forever ended pain as, before that day, even amputations were performed with the patient fully conscious. "Letheron", unknown to everybody but Morton and Elizabeth, is simply highly rectified sulphuric ether - cleaning fluid - easily obtainable at a pharmacy. By keeping the secret, Dr. Morton could be rich, but he had rather be poor than see a girl strapped to an operating table under the knife of Dr. Warren (Harry Carey), and he reveals his secret to a group of surgeons in the hospital operating theatre. With his secret out, and all hope of personal reward gone, with the possible exception of proceeds from his glass inhaler, he gets the news that Congress has voted him a reward of $100,000, and also learns that the patent on his inhaler has been infringed. President Pierce, under pressure from newspapers inflamed by jealous medical rivals of Morton, refuses to sign the bill until Morton has proven patient infringement.