Harry Donalds is a lonely bartender working in New York City. One night, a beautiful woman named Lora comes into the bar where he works, looking to get drunk on her last five dollars. Harry talks her into going out to eat and talk about her troubles. She tells him that her boyfriend, rich stockbroker Roy Brochard, has finally admitted that he does not intend to leave his wife for her. She has been walking all day in the Manhattan heat, and asks him if she can use his shower and stay with him until she gets back on her feet. He agrees, and Lora moves into his apartment, where she cleans, cooks, and begins a sexual relationship with him. Harry is happy with this arrangement, although Lora keeps mentioning how fabulous her life was with her wealthy ex.

Then one day Harry comes home to find that Lora has bought a hunting knife to kill Roy, both in revenge and to prevent him from doing the same thing to another girl, now that she knows he has a new girlfriend. She wants Harry to lie for her so she has an alibi when she denies the crime, but he refuses. Lora leaves.

Lora returns a few days later, saying she has changed her mind about the murder. Nevertheless, she does kill Roy, and Harry hears about it on the news. He agrees to lie for her. Their lovemaking becomes violent, with Lora asking to be punished for her crime and Harry playing on his anger over her lie and becoming quite violent.

Lora tells Harry she wants to marry him, but he worries that now that she is a murderer, perhaps she might kill again...