Leona Stevenson is the spoiled, bedridden daughter of wealthy businessman James Cotterell. One day, while listening to what seems to be a crossed telephone connection, she hears two men planning a woman's murder. The call cuts off without Leona learning very much other than it is scheduled for 23:15, when a passing train will hide any sounds. She calls the telephone company and the police, but with few concrete details, they can do nothing. Complicating matters, her husband Henry is overdue and their servants have the night off, leaving her all alone in a Manhattan apartment.
