Please Murder Me

Please Murder Me is a 1956 American film noir directed by Peter Godfrey, and starring Angela Lansbury, Raymond Burr, and Dick Foran. The film, which is in the public domain, is available for free viewing online on the Internet Archive, YouTube, and on other streaming sites.
Plot.
Defense lawyer Craig Carlson (Raymond Burr) buys a pistol at a pawn shop and travels to his office, where he deposits the gun in a desk drawer with a file folder, then begins to dictate into a tape recorder. Directing his message to District Attorney Ray Willis (John Dehner), he reveals that he anticipates being murdered within an hour, and begins to tell his story in extended flashbacks.
The memories begin with his explanation to his war buddy and best friend Joe Leeds (Dick Foran) that he is having an affair with Leeds' wife Myra (Angela Lansbury), who wants a divorce. Joe asks Craig to give him a little time to think the matter over. Days later at his own office, Joe finishes writing a letter and gives it to his business partner Lou Kazarian to mail. Joe phones Myra telling her he will be home soon to discuss something. There, he confronts Myra in their bedroom, where a door is closed and a gunshot is heard. Police investigate Joe's death. Myra explains that Joe became irate and threatened her physically, forcing her to shoot him in self-defense. Craig is also on the scene, having arrived before the police and acting as Myra's lawyer.
In the ensuing trial, DA Willis allows the police to present their evidence that a physical struggle did not occur as she'd said. Willis notes that Myra was not employed when she first met Joe, a successful businessman with a good amount of life insurance. In her defense, Craig attributes Myra's inconsistencies regarding the night in question as post-traumatic hysteria. In his closing argument, Craig claims the money motive in Willis' case is not valid because Myra was in love with another man — a revelation that could inspire Joe to cause Myra premeditated harm. Craig then reveals that he himself is Myra's lover.
The jury finds Myra not guilty. She and Craig throw a party to celebrate with friends. When Lou arrives, he reveals privately to Craig that he had forgotten to mail Joe's letter, which was addressed to Craig. Joe discloses in the letter that Myra did indeed marry him for his money, but that she was actually in love with an artist, not with Craig. Joe had decided to ask her to stay married, in part to save Craig from her. Craig then remembers Myra mentioning that an "old friend", an artist named Carl Holt, had visited her in jail during the trial.
Craig goes to see Holt, who explains his long relationship with Myra, interrupted by her marriage to Joe, and states his gratitude and admiration for Craig in his defense work in Myra's trial, especially his posing as Myra's lover as a tactic. Craig later confronts Myra with Joe's letter and his talk with Holt. She admits that she does intend to go on with Holt now she is free.
Accusing her of costing him his best friend, the love of his life and his profession all at once, Craig tells Myra she will pay for her crime regardless, because he will force her to murder him. Myra is incredulous, but Craig soon puts a plan in motion, developing a friendship with Holt, even employing him to paint a portrait to delay Myra and Holt's departure to Europe to marry. All the while, Craig taunts Myra that he will reveal all the evidence to Holt and let him decide if he wants to marry a murderess. As well, Craig meets socially with DA Willis, discussing Myra's case, and lets Myra see them together.
Craig concludes his story being dictated into the tape recorder by saying he has arranged to meet Myra at the office at 12:30 am, which soon arrives. Hearing a knock at the office door, Craig leaves the recorder running and hides the microphone behind a desk photo of himself and Joe, then lets in Myra. He shows her the file he says is full of evidence he's compiled against her, and then sets down the pistol on the desk.
As he starts to make a phone call to Holt, Myra, successfully driven to desperation, takes the gun and shoots Craig, who falls to the floor. Using a handkerchief, she hangs up the phone and wipes her fingerprints from the gun, which she puts in Craig's hand. She finds the file is full of nothing but blank sheets of paper. When DA Willis arrives, she explains that Craig has shot himself. After checking that Craig is in fact dead, Willis learns that Myra had an appointment with Craig for 12:30, then tells her Craig had invited him to come at 12:40. He finds the microphone and recorder, then stops and rewinds the tape. As he begins to play Craig's recording, Myra starts crying, defeated.