Wiretapper (1955)

U.S. Army electronics expert Jim Vaus, Jr. is sentenced to a stockade term for unauthorized use of government equipment. He keeps this from his fiancée Alice, pretending he has been overseas when he is discharged, and they are married.. He opens an electrical-engineering company and becomes involved with a gangster mob headed by Charles Rumsden. She begs him to quit but he is useful to the crooks: discovering wiretaps, setting up alarm systems, and even saving a hoodlum's life by disconnecting a time bomb. Gang-member Tony urges Jim to invent a device that could tap lines carrying race results and delay them so they could make some big money on post-race betting. After Tony is killed by a fellow mobster, Alice persuades Jim to attend a tent meeting held by evangelist Billy Graham. Graham's sermon and words so inspire Jim that he gives up his criminal activities.