Before I Hang is a 1940 American horror film released by Columbia Pictures, starring Boris Karloff. The film was directed by Nick Grinde (under the working title The Wizard of Death) and was one of several films Karloff starred in under contract with Columbia. Plot Dr. John Garth (Boris Karloff) is on trial for murder after performing a mercy killing on an elderly friend. In the trial, he reveals that he had been researching a cure for aging but had not had time to perfect it before his friend's pain became unbearable. Despite his pleas for mercy, the judge sentences him to be hanged in three weeks' time. As he awaits his execution, Dr. Garth is allowed to continue his experiments, thanks to support from the prison warden (Ben Taggart) and another scientist who is interested in his research, Dr. Ralph Howard (Edward Van Sloan). Using the blood of a recently executed prisoner, they succeed in developing a serum that will reverse the effects of aging and decide to test it on Dr. Garth immediately prior to his execution. As he is being taken away to the gallows, however, the prison receives a call informing them that Dr. Garth's sentence has been commuted to life imprisonment. At the same moment, the serum's effect on his body causes Dr. Garth to collapse. When Dr. Garth awakens in the prison medical ward, he discovers that the serum has reversed some of the effects of aging on his body, including the graying of his hair, the appearance of his face, and his physical fitness. Encouraged, he decides to perform another test of the serum, this time on Dr. Howard. As he is preparing Dr. Howard for injection, however, Dr. Garth is overcome by a sudden urge to kill induced by the presence of an executed murderer's blood in his system. After he strangles Dr. Howard, a wandering prisoner enters the room and, after a struggle, is also killed by Dr. Garth. When the prison authorities discover Dr. Garth, who does not remember committing the murders, and the two bodies, they believe that the wandering prisoner killed Dr. Howard and attempted to kill Dr. Garth. As a result, Garth is labelled a hero and granted a full pardon. He returns home to live with his daughter, Martha (Evelyn Keyes), and continues his research on the anti-aging serum. Wishing to test it further, he confronts