Radio listeners could enter a contest explaining who killed Jenny and her companion Carter in this mystery, but they had to see the movie in order to know the author's ending.
Wanted gangster Gary Curtis (Ricardo Cortez) is in Los Angeles and follows Jenny Wren (Karen Morley) to the bank, where she insists the bank executive Priam Andes (H. B. Warner) invite three other men to a dinner party that night at his ocean-front estate. She plans to leave the country and retire. Curtis visits her apartment, saying he wants to rent it. At the Andes ranch Jenny asks for $50,000 from Will Jones, $100,000 from Priam, $25,000 from Eddie Mack, and $250,000 from Herbert Walcott, who is running for senator. She claims she can stop the marriages of Mack and Jones, and she has writings from Walcott and Priam sufficient for blackmail. Priam suggests that Curtis will give her all she wants; but she is tired of that game. She tells (and a flashback shows) how she rejected a proposal of a young millionaire who wanted to marry her without his money, causing him to jump off a cliff. She throws away the fraternity pin he gave her, but she sees his face in the dark.
In the night after a scream Jenny is found stabbed by a dart. Priam's sister Faith (Pauline Frederick) calls to report the murder but is cut off. A landslide has blocked the road. Curtis says that with his record he does not want the police there, and so he and his men must solve the murder themselves. Jenny's sister Esther (Anita Louise) is found in Jenny's room unconscious. She and young Frank Andes plan to marry, but Faith strongly objects to her. Curtis by questioning discovers that Walcott, Vayne (Ivan F. Simpson), and Frank each went to Jenny's room. Suddenly the lights go out, and the ghostly face appears again. Vayne explains that the boy was his son and that he used the death mask to scare Jenny; Vayne wanted to kill Jenny and wished he had, but then he dies of a heart attack. When Esther is found wounded by a dart, Curtis sends everyone to their rooms while he and his man search for Jenny's female companion Carter. From a nearby cliff they discover a secret tunnel and Carter killed by a dart along with the death mask. Curtis figures out that Faith is trying to kill Esther, and he gets Frank to show him the passageway just in time for him to stop Faith from pushing Esther off the cliff. Knowing she is caught, Faith jumps off the cliff, and Frank embraces Esther.
This multiple blackmail gets the audience suspecting several people, but the unlikely murder motive is family pride, thus keeping everyone in suspense until the end. Jenny turns out to have been killed by mistake.