The problem with the mystery stories concocted by Jason Cord (Milton Berle) 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 Cord (Mary Beth Hughes), whose boss, Brennan (Reginald Denny), 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.

In the opinion of his wife Patricia, mystery writer Jason Cordry is incapable of completing a single task. Knowing this, she listens with skepticism as he tells her his latest idea for a novel: A wealthy broker commits suicide and a stranger proposes to the broker's unscrupulous partners that he make the suicide appear to be a murder in exchange for a fee of $50,000. The partners agree to the scheme and "borrow" $50,000 from the company coffers to pay the stranger. Pat interrupts Jason's story to ask him how he intends to have the stranger elude capture. When Jason fails to provide a satisfactory answer, she flies into a rage. Later, at the Hollywood brokerage office where Pat works, broker Tom Mardley threatens to have his three partners, Lawrin, Crole and Brenner, arrested for stealing money from their investors unless they return the money. Mardley then takes $15,000 from Lawrin as a downpayment on the return of the stolen money. The following day, Jason shows up at Pat's office to tell her that he has come up with an ending for his story. Just as he is about to tell her what it is, though, Pat learns that her bosses are on their way down, and she hides Jason in the board room. While the bosses hold a meeting in the board room, Jason remains hidden in a closet. During the meeting, Jason overhears Lawrin and Crole report to Brenner that Mardley has committed suicide and that they have the $15,000 he took from Lawrin. As the men try to figure out how they will escape being discovered by the police when their books are checked, Jason, who recognizes the similarity between his mystery plot and that of the brokers' predicament, steps out of the closet and assumes the role of "the stranger" in his story. The men, desperate for a solution, take up Jason's proposition to make Mardley's suicide appear to be a murder and pay him $15,000. Jason then hurries to Mardley's apartment at the Clexton Terrace, where he takes the suicide note and rearranges the apartment so that it will appear obvious that Mardley was murdered. On his way out, Jason makes certain that the elevator operator remembers his face. He then disguises himself as a foreign dignitary and posts an announcement in the newspapers that the wealthy and generous Baron La Roux has arrived in town and will be holding court at the Clexton Terrace Apartments. As part of his plan to confuse the elevator operator, who will be the key witness in the murder trial, Jason returns in diguiese to the hotel to have his picture taken with the boy. Jason's plan goes awry, however, when the elevator boy immediately recognizes Jason behind his disguise. Charged with Mardley's murder, Jason is arrested and thrown in jail. In his cell, Jason reads in the newspaper that in college Mardley was a left-handed baseball pitcher and, remembering that he found the gun in Mardley's right hand, concludes that Mardley was, indeed, murdered. Determined to clear himself of the charges, Jason disguises himself as his cellmate Petie and walks out of his jail cell. Jason then goes to Pat's brokerage office, where he asks the partners for help in solving the murder. The men show no interest in helping Jason, and Lawrin pulls a gun on him. Jason manages to escape, and when he meets up with Pat, she recognizes the gun as Mardley's. While rummaging through Mardley's apartment looking for his gun license, Jason is discovered by the police and is taken to court. At his trial, Jason cleverly wins his acquittal when the elevator boy is unable pick him out of a line-up of movie extras disguised as Baron La Roux. Not entirely satisfied with a simple acquittal, Jason surprises the court by proving that Mardley was forced to write his alleged suicide note by the man whose telephone number is scribbled on the note. Jason then accuses Brenner of the murder, and when Brenner tries to flee the courtroom, his guilt is proven. With the mystery solved, Jason returns to his writing and begins a new story. Pat asks him how this one will end, and when he says that he does not know, she loses her temper.