Summer Lovers

Michael and Cathy, a young couple who have just graduated from college, have known each other about 10 years and have been together about half that time. They arrive on a nameless Greek island to spend two months for the summer of relaxing before going back to the real world. When they visit a nude beach crowded with other young tourists (a combination of American, British, French, German, Italian, Spanish, as well as Greek), they are hesitant at first but find themselves getting caught up in the uninhibited energy that surrounds them.Cathy reads a book of sexual techniques, then ties Michael to the bed and drips candle wax on his chest that evening. Michael is very uncomfortable by her experiements. Cathy comments that everyone thinks she's "such a Goody Two-Shoes" but she wants a little more adventure.Michael, who says he has never been with another woman, keeps noticing Lina, a French archaeologist on temporary assignment at the nearby Akrotiri excavation. One day, at the beach without Cathy, he gets his chance to talk to Lina and ends up starting an affair with her. He then feels so guilty that Cathy immediately notices something is wrong, and he admits what he has done, insisting that he still loves Cathy.Cathy is naturally disturbed by this, but tells him to "get it out of his system", which he takes as permission to return to Lina. Cathy then goes to a local bar intending to sleep with another man as a way to get revenge against Michael for cheating on her. But in the end, she chickens out after getting picked up by an amorous local boy. When Michael comes home later after seeing Lina again, Cathy says she wants out of the relationship.The next day, Cathy goes to Lina's home to confront her. Lina assures Cathy that she does not intend to take Michael away from her, which seems to calm Cathy somewhat. Lina and Cathy end up spending several hours together getting acquainted, and talking, and find themselves fascinated by each other's work; Lina's archeology and Cathy's photography.Michael is confused when he learns that the two women are developing a friendship, but he quickly recovers and the three of them spend a few days gradually getting closer. Cathy knows Michael is still sleeping with Lina from time to time, but seems to accept it, although she says it would be difficult for her to see them in bed together. Nevertheless, she tolerates increasing signs of affection between Michael and Lina in her presence.One evening, Cathy encourages Michael to kiss Lina. He gives Lina a light peck, but Cathy says it isn't convincing. He gradually turns up the heat while watching Cathy intently for her reaction. He then kisses Cathy, checking to see how this makes Lina feel. The three end up spending the night together in bed. Lina moves in with them, and they continue enjoying the island paradise as a threesome.Over the next several days, Michael, Cathy, and Lina enjoy their "household of three" and spending nights with all three of them having sex with each other. Just as the fantasy seems to be a total success, the natural complications of domestic life, like who does the laundry or dishes, come to the foreground. The three work through these problems, but then things come to a head when Cathy's mother appears on a surprise visit and is shocked when she sees all three of them in a comprompising situation, which snaps everyone back to reality. Cathy tells her mother she's never been happier in her life. Although Lina claims to be bad at relationships and prefers just "screwing", the three actually seem to be falling in love all around.Aside from Lina's comment that she prefers just "screwing," the sexually charged plot is underscored by a number of other instances of openly sexual comments and humor.Finding herself in an intense relationship, and uncertain about her future with them, Lina begins to fear getting hurt when the summer ends and her American friends will return home. Michael and Cathy tell Lina that it doesn't have to end, but they don't go into any details. To avoid getting too close to her new friends, Lina disappears with another young man she met at the beach.Cathy and Michael are distraught, and spend several days searching for Lina. Eventually they conclude they won't find her as long as she wants to remain hidden. But their memories of Lina loom over everything they try to do, and they can no longer enjoy their time on the island. They pack up to return home, even though they have three weeks remaining prepaid on their bungalo rental.Lina finds her fears are outweighed by her feelings for the Americans, and returns to reunite with them, only to discover they have already gone. She races to the airport and intercepts them just as they are about to board the plane. Overjoyed at seeing her again, Cathy and Michael return to spend the last three weeks of their summer with her.

Question: Who makes a surprise visit?
Answer: Cathy's mother