Forty Naughty Girls (1937)

Police Inspector Oscar Piper and Hildegared Withers attend the opening night of a Broadway play in New York City, and the show's press agent is murdered before the curtain goes up. But the show must go on and while Piper is busily investigating the killing while the play goes on, the play's librettist is shot. Piper and Withers are in and out of dressing rooms, in audience cubicles belonging to the producer and press agent, and in the basement storeroom, and far stage left and right working on finding the killer before the curtain drops.