John Vincent, a respected member of the business community, is about to marry his sweetheart Louise when his past comes back to haunt him. Unknown to his fiance or friends, years earlier Vincent escaped from Dartmoor, an English prison in which he was an inmate. Twenty years later, his old cellmate, Gobel, tracks Vincent down in Los Angeles and demands $100,000 for his silence. After pacifying his blackmailer with a $5,000 down payment, Vincent plots the perfect crime to eliminate his tormentor by shooting Gobel and placing the blame on Romero, the lover of Gobel's wife Virgie. To accomplish his plan, Vincent signs Romero's name to an incriminating document and then steals his gun. Before he is able to confront Gobel, however, Romero, who wants the blackmail money for himself, decides to poison Gobel by substituting poisoned pills for his medication. As Vincent enters the house, Gobel takes his pills and, after fiercely defending himself from Vincent's attack, suddenly falls to the floor. Not realizing that Gobel is already dead, Vincent shoots him with Romero's gun and Romero is arrested for murder and sentenced to die. Desperate to save her lover, Virgie begs Trent, Vincent's good friend and attorney, to reopen the case. With Louise's help, Trent discovers Vincent's part in the murder, resulting in his arrest and death sentence. Horrified at having incriminated his friend, Trent works untiringly to find him innocent. Finally, hours before the execution, Trent learns that Virgie has died after taking some of her husband's medicine. Realizing that it must be poison, Trent orders an autopsy of Gobel's body which discloses that he died of poisoning. Trent and the district attorney then trick Romero into confessing, but he is mortally wounded while trying to escape. Exonerated of Gobel's murder, Vincent returns to Dartmoor to complete his sentence, but before leaving, he frees Louise to marry Trent.