The action takes place in the late 1930s. 30 year-old Mary Panton, whose extraordinary beauty has always been one of her greatest assets, has been a widow for one year. Her late husband Matthew, whom she married when she was 21 because she was really in love with him, turned out to be an alcoholic, a gambler, a womanizer, and a wife-beater. However, Mary Panton patiently endures all the hardship and pain inflicted on her by her husband (including him having sex with her while drunk). When he drinks and drives he has a car accident and eventually, a few hours later, dies in Mary's arms. This, she concludes, is a blessing for both of them.
The Leonards—a couple who never appear in the novella—offer her their 16th century villa on a hill above Florence, Italy, to stay there for some time, and she gladly takes them up on it. The old villa is staffed by two people—Nina, the maid, and Ciro, her husband, a manservant—but otherwise empty. Mary, whose parents are both dead, enjoys the solitary life up at the villa. Occasionally, she joins other highbrow residents of, and visitors to, Florence for a party or luncheon. Also, she likes driving round the countryside in her car. So far it has never occurred to her to take a lover—whether this is because she considers it immoral, because it may cause a scandal or because she does not feel the need remains obscure; what she does say is that it has been easy for her to do without one because she has never been tempted.
During dinner at a restaurant together with some of her acquaintances—among them the old Princess San Ferdinando, an American who is said to have been quite a loose woman in her day—they listen to a young man playing the violin. He is ridiculously dressed up in folkloristic clothes and not good at all at playing the instrument. At the end of the evening, the Princess tries to set Mary up with Rowley Flint, a young Englishman of independent means whose reputation is very bad, by asking her to give him a lift back to the hotel where he is staying. Flint actually makes a pass at her, but she rejects him and just laughs at him when he even proposes to her: They both seem to know without speaking that this proposal of marriage could not be meant seriously.
After she has dropped him off at the hotel, she drives back home. On her way up to the villa, although it is late at night and dark, she stops to have a look at the scenery. She senses that there is someone else quite close to her. This other person turns out to be Karl Richter, the fiddler from the restaurant, also admiring the view. They strike up a conversation, and Mary learns that he is a 23 year-old Austrian art student who has recently fled the country because he was being persecuted by the Nazis, and now, without a passport or any other documents, is staying as an illegal immigrant in a shabby rented room at the foot of the hill quite close to the Leonards' villa.
Mary takes pity on the poor boy and, on the spur of the moment, asks him if he wants to come up with her to have a look at the precious paintings in the villa. Once there, it turns out that, due to his having no money, Richter has not had dinner. With the servants long gone to bed, Mary fixes him some bacon and eggs. They have wine with their improvised meal.
One thing leads to another, and they end up in bed. Earlier that same night, when taking leave of Flint, Mary confessed to him that if she ever had sex outside marriage it would have to be with a poor man whom she pitied; and it would only be once. This kind of foreboding now becomes reality.
When Mary thinks it is time for Richter to leave and the latter, to her dismay, asks when he will be able to see her again, the idyllic situation quickly deteriorates. Mary remembers the revolver her suitor, 54 year-old Sir Edgar Swift, has forced upon her as a means of protection. When Richter starts insulting and threatening her, she pulls it out of her handbag, aims it at Richter, but then cannot summon up the courage to pull the trigger. She wants to do him good, advising him to try and escape to Switzerland, but to no avail. Richter feels utterly humiliated when he learns from Mary that she has only slept with him out of pity. He says he saw a goddess in her, but now she is just a whore for him. It is then that Mary Panton's nightmare begins: Richter with a swift gesture picks her up and roughly throws her on her bed, before covering her face with kisses. She tries to get away from him but as he is much stronger than her, she is powerless and ceases to resist. A few minutes later in a fit of remorse over what he sees as the impossibility of life since escaping his homeland Richter announces You asked me not to forget you. I shall forget, but you won't, then in the dark he shoots himself through the breast with Swift's gun. There is only little blood due to the internal haemorrhage Richter inflicted on himself.
Nina, her maid, hears the shot and presently knocks at her bedroom door. Mary panics and sends her away without opening. Then she phones Rowley Flint and asks him to help her. As taxis are not available all night, Flint borrows the hotel porter's bicycle and then walks up the hill to the villa. They have to think fast as there are only a few hours left before the break of the new day. Mary Panton is prepared to accept full responsibility for her actions. But then Flint has the idea that the two of them might just as well try to dispose of the body.
Flint and Panton drag the body out of the house and into Mary's car. Then they drive along the highway and finally turn into a country lane. There, in the dark of the night, Flint dumps the body. A dangerous situation arises when a car full of drunk Italians approaches. The driver has difficulty passing Mary's car and has to slow down almost to a halt. When the party see Mary and Flint, who are embracing each other, pretending to be lovers, they start singing "La donna è mobile" and drive on. On the following morning, in broad daylight, Flint returns to this spot to throw away the revolver, which they forgot the night before.
On the following morning Mary Panton sleeps almost until noon. She has an invitation for luncheon, and Flint has inculcated upon her not to show any signs of panic or fear or whatever, so she goes there. Her guilty conscience is her constant companion though.
The situation becomes even more complicated with the impending arrival of Sir Edgar Swift, who has known her and her parents since she was a little child, and who politely retreated when she got married to Matthew Panton. Now Swift has gathered new hope ever since she has been widowed. Shortly before Richter's suicide he informs her of his impending promotion to a high government post in colonial India. As he will have to do a lot of entertaining, he is looking for a suitable wife, and he actually proposes to Mary before he flies off to Cannes on urgent government business. Mary tells him she will give him an answer when he is back in Florence.
When Swift comes up to the villa Mary has already made up her mind to confess everything to him. After listening to her story he says that he forgives her and that he still wants to marry her. At the same time, however, he declares that he will not be in a position to accept the post he has been so eager to get, claiming that if his wife's criminal past caught up with them, the ensuing scandal might even jeopardize the Empire. He suggests the following course of action: He retires, they get married, and then they move to the French Cote d'Azur. Mary, however, objects to that: She tells him bluntly she is not in love with him and that she could not stand his presence 24 hours a day.
After Swift has left, Flint turns up at the villa again, remarking that he does not "keep all [his] goods in the shop window": He owns an estate in Kenya, and has also read Dr Johnson, so all of a sudden he does appear eligible to Mary. She remembers the previous night, their emergency embrace in the dark country lane, which she found not wholly unpleasant. And, agreeing with him that life is all about taking risks, she decides to accept his proposal this time.