After a fight with his wife on their anniversary, Scott Henderson, a 32-year-old engineer, picks up an equally unhappy woman at Anselmo's Bar in
Manhattan, and they take a taxi to see a stage show. The woman refuses to tell him anything about herself. The star of the show they are watching, Estela Monteiro, becomes furious when she notices that she and the mystery woman are wearing the same distinctive hat. When Henderson returns home, he finds Police Inspector Burgess and two of his men waiting to question him; his wife has been strangled with one of his neckties. Henderson has a solid alibi, but the bartender, taxi driver, and Monteiro remember him but deny seeing the phantom lady. Henderson cannot even clearly describe the woman. He is tried, convicted, and sentenced to death. Carol Richman, Henderson's loyal secretary who is secretly in love with him, sets out to prove his innocence. She sits in Anselmo's Bar night after night, staring at the bartender and unnerving him. Finally, she follows him home one night. He confronts her on the street and lets slip that he has been bribed to lie about the night of the murder. He runs into the street and is killed by a passing vehicle. Later, Burgess offers to help Carol unofficially, believing that only a fool or an innocent man would have stuck to such a weak alibi. Burgess provides Carol with information about the drummer at the show, Cliff, who had tried to make eye contact with the phantom lady. Carol dresses provocatively and goes to another of Cliff's shows. Flirting with Cliff during the performance, she manages to capture his attention. They rendezvous afterwards, visit an underground jam session, and go to his apartment. Somewhat drunk, Cliff brags that he was paid $500 for his false testimony. He accidentally knocks over her purse and, among the spilled contents, finds a piece of paper with details about him on police letterhead. He accuses her of misleading him. Carol escapes, leaving her purse behind. After she has gone, an unidentified man arrives, accuses Cliff of admitting to the bribe, and strangles him to death. The man turns out to be Jack Marlow, Henderson's best friend, who has ostensibly returned from South America to help Carol save Henderson. He secretly works to frustrate Carol's efforts, while hiding his own deteriorating mental state. Carol tracks down Monteiro's hatmaker and discovers that one of her employees copied the hat for a regular customer. With Burgess away on another case, Carol and Marlow go to see the milliner's client, Ann Terry. They discover her under a doctor's care, having suffered a breakdown several months earlier when her fiancé died suddenly. Carol is unable to get any information from her, but does find the hat. Marlow takes Carol to his apartment, supposedly to wait for Burgess. While she is freshening up, Carol finds her missing purse and the paper with Cliff's particulars and realizes Marlow is the killer. He admits to killing Mrs. Henderson after she refused to run away with him. Burgess arrives just in time to stop Marlow from killing Carol. Marlow throws himself out the window to his death. Henderson is freed, and the door is open to a relationship with Carol. ==Cast==