Audrey Totter and Paula Raymond, each of whom have relatively little screen time, are both billed as stars with Walter Pidgeon and John Hodiak -- though all are billed after the title, like a no-star B-movie. Meanwhile, Karl Malden, especially, and Everett Sloane, to name two who are centrally involved, are pretty far down the cast list. A good insight into who the studio (MGM) was trying to build up with bigger publicity at the time.
shareWell, also, I think it was some kinda crazy unwritten rule back in the day (and sometimes today, even) -- if there are female characters at all in the movie, there had to be a "leading lady" in the credits. Maybe to draw in female viewers, who were to assume they'd get to identify with the leading lady, or to let guys know there'd be pretty woment to see in the film???
Also, at least with Audrey Totter, I think this might be as much a case of capitolization on a name as building it up. Totter had made her first film about seven years prior and had appeared in what were some either fairly or definitely major films -- most prominently The Postman Always Rings Twice. Making her a "leading lady" in this film might have done something for her, but it might have done at least as much for the movie (not meaning to suggest she was a big, big star at the time, but that her name was probably pretty well-known at that point).
Matthew