The Phantom of 42nd Street (1945)

An actor's dead body is discovered after a theatrical performance, clearly the victim of foul play. Theater critic Tony Woolrich (Dave O'Brien) suddenly finds himself behaving like an amateur sleuth as he attempts to solve the vicious crime. Actress Claudia Moore (Kay Aldridge) is the prime suspect, but, when further deaths occur, it's clear that she too is in danger. Lost in a labyrinth of clues, Woolrich struggles to find the killer before he gets to Claudia -- the woman Woolrich loves.