I thought it was Lloyd Nolan who played Martin Kane. Or did he replace Tracy, or the other way around?Lee Tracy took a turn at playing Martin Kane, Private Eye on radio and TV. Some of the early TV episodes are on Youtube and they're quite a hoot. The show was broadcast live, so if someone bumped into the scenery there were no re-takes or edits. The TV show was sponsored by United States Tobacco Company and featured one or two integrated commercials per episode, where the case would be discussed in the local tobacco shop while the proprietor extolled the virtues of Model, Old Briar, or Sano cigarettes. Kane lit a pipe in the title scene and kept it going just about all the way through the show.
TV screens in the early 50s were tiny by our standards, so the show is presented almost entirely in close-up, and all the action takes place indoors.