Two middle-aged sisters, Marta, Aurora Bautista, and Verónica, Esperanza Roy, run an inn in a quiet Spanish village that caters to travelers seeking a respite from daily life. Their devout religious beliefs color every interaction, especially when a British guest named May, Loreta Tovar, sunbathes topless on the terrace. A sharp clash over modesty escalates quickly, and May is pushed down a staircase, crashing through a glass window and dying.
With the body hidden, Laura Barkley, Judy Geeson, May’s sister, arrives at the inn and is told that May checked out and paid her bill earlier that day. Laura decides to stay for a while, hoping to locate May.
The next day, Helen Miller, Lone Fleming, checks in, and Verónica goes to visit Luis, with whom she is having an affair, and the two have sex. Afterward, Verónica confesses to Luis that Marta has discovered money missing, which she had given to Luis.
Meanwhile, Marta spies on several young men skinny-dipping, taking in the village’s slower, sunlit rhythms from a distance. Later, when Helen returns late at night, she clashes with Marta, who has forbidden guests to arrive back after 11pm. The confrontation ends with Marta stabbing Helen to death.
The next morning, Norma, Blanca Estrada, an American woman with an infant, arrives. Bothered by Helen’s disappearance, Laura checks out of the inn and moves to a different hotel. She then meets with a local police chief who reveals that Marta’s fiancé disappeared on their wedding day years before, adding a layer of haunting history to the inn.
That night, Laura’s presence stirs tension as Marta and Verónica are found in the kitchen with Norma’s baby. Marta chastises Norma for being a single, unmarried mother. Norma and Marta clash, and Norma is slain when Marta stabs her in the back. Verónica discovers a letter in Norma’s belongings to her husband about a pending divorce, revealing Norma’s true marriage status, which leaves Verónica shaken, even as Marta remains unmoved.
Laura breaks into the inn again to search for evidence, investigating the large wine vats in the basement, but she flees when the sisters hear her. The next day, Laura returns with Eduardo, Víctor Barrera, posing as her husband who has just arrived, and rents a room. Marta grows suspicious, believing she has seen the man before in town.
During a meal, a guest falls violently ill; her husband notices an odd piece of meat on her plate and contemplates handing it to the police. Late that night, Eduardo goes to check the basement. In one of the vats, he discovers pieces of flesh and bones floating in red wine, along with Norma’s severed head. As he steps away, Marta stabs him to death.
Back at the local police station, it’s determined that the piece of meat is indeed a chunk of flesh with an eyeball attached, a disturbing clue stirred up by Laura’s earlier probing of the vats. The police and a band of villagers hurry to the inn. Laura returns to search for Eduardo and finds him dead in the sisters’ bedroom. The two women bind and gag her, then corner her against a window. She struggles free enough to pull back the drapes, revealing both the police and the watching villagers outside as the scene reaches a chilling, televised-like close.
