Perry Mason represents a man who wants to keep his cat and then saves another client by revealing the murderer.
Frank Oafley (Craig Reynolds) sees Douglas Keene (Carlyle Moore Jr.) kiss Wilma Laxter (Jane Bryan) goodnight at 2 a.m. The angry old Peter Laxter (Harry Davenport) tells Wilma that men want to marry her for his money. He calls Perry Mason (Ricardo Cortez) to change his will, and he cuts out Wilma to see who loves her. Peter also insists the caretaker Ashton (George Rosener) keep his job and his cat. Nurse Louise DeVoe (Nedda Harrigan) tries to listen and is kissed by Frank. Wilma calls on Mason about the will, but Keene wants to marry her anyway. Newspapers announce that millionaire Peter Laxter was killed in a fire.
Ashton asks Mason to keep Sam Laxter (William Elliott) from taking away his cat; Ashton has money and is followed. Mason writes to Sam Laxter about the cat. Sam's lawyer Shuster (Clarence Wilson) asks Mason for a waiver from Wilma not to contest the will. Paul Drake (Garry Owen) investigates for Mason, learning that Ashton has a safe deposit box and one for his brother. Mason asks DeVoe about the fire; she suspects Sam. Mason asks District Attorney Burger (Guy Usher) for an autopsy on Peter Laxter to see if he died before the fire. Mason and the D. A. find Frank with scratched hands; he says he was digging for diamonds. Sam comes in with a bruised face. Mason and the D. A. find Ashton dead in his room. Mason goes to Wilma, who has the cat. Ashton asked her to care for it, and Keene went to get it. Mason takes the cat to Della Street (June Travis). Mason finds DeVoe dead in her apartment, and he learns that she got married that night. Sam, Frank, and Keene were there. Mason and Drake find a blood-stained suit at Keene's apartment. Keene is charged with the murders of Ashton and DeVoe. The minister who married DeVoe and Frank hit the car of Ashton's brother. Keene calls Mason and says he found DeVoe dead.
At the hearing Frank says Keene knew about the diamonds. Mason implies that Frank was scratched by the cat. A doctor testifies that Peter Laxter was dead before the fire. Watson Clammert is arrested with a million dollars. Mason calls him as a witness, and he is Peter Laxter. Mason explains that Peter Laxter knew someone was trying to asphyxiate him; so he escaped and put a dead body in his bed. Peter Laxter saw Ashton go to DeVoe's. Frank killed Ashton and found the diamonds in his crutch. Frank took Ashton's body to his room and put cat tracks on it. Peter Laxter visited DeVoe; when she pulled a gun, he killed her in self-defense. Sam came in and hid, as Keene came in. Sam took Ashton's car to Keene's room and stained his suit with blood. Keene is released, and Frank is arrested for killing Ashton.
The intricate plot of this mystery keeps the audience guessing until Perry Mason explains how all the details fit together, offering an intriguing exercise in figuring out clues and motives.