Dick Powell starred as Richard Diamond, in the radio series as a light-hearted detective who often ended the episodes singing to his girlfriend, Helen Asher (Virginia Gregg). Other regular cast members included Rick's friend and former partner on the police force, Lt. Walter Levinson, played variously by Ed Begley, Arthur Q. Bryan, Ted DeCorsia and Alan Reed, and Wilms Herbert as Walt's bumbling sergeant, Otis. (Herbert also "doubled" on the show as Helen's butler Francis.) The show began airing on NBC Radio on April 24, 1949 and continued until December 6, 1950. Its theme, "Leave It to Love", was whistled by Powell at the beginning of each episode.