Over My Dead Body (1942)

The problem with the mystery stories concocted by Jason Cordry is that he can never figure out who's guilty. Stuck, as usual, he takes his latest unfinished "who-dunit" to the office of his wife, Patricia Cordry, whose boss, Brennan, doesn't know she is married. Hidden in a closet, Jason overhears Brennan and his partners discussing a situation which exactly parallels his new story. He steps out when the discussion reaches the point of his story's current progress and, seeing a chance of finding an ending to his story, offers to make a suicide look like a murder. He soon finds himself the central figure in a front-page murder trial before he proves the supposed suicide to have been an actual murder - committed by one of the victim's partners.