The four-year-old marriage of artist Timothy Frischer and his wife Lily is shaky, so the youthful city dwellers agree to spend the summer together as a trial period at an isolated beach house on Choke Cherry Bay. They quarrel shortly after arriving and, when Lily threatens to leave, Timothy throws her suitcase into the water. Frustrated with his childish immaturity, Lily gets in the car to drive away, but Timothy jumps onto the moving vehicle, hangs onto the windshield and cajoles her into stopping. Although she is weary of his antics, she is also amused and decides to remain. Their landlord and only neighbor is Major Evelyn Ritchie, a Vietnam veteran and amputee about ten years their senior who owns two highly trained Doberman pinschers. When the Frischers meet Ritchie, Timothy fires off questions about garbage and other practicalities and repeatedly interrupts the eager, friendly chatter of Lily. Although Ritchie chuckles at the Frischers’ gentle bickering, Lily intuits that he is growing annoyed by Timothy’s questioning and apologizes for their enthusiasm. Ritchie seems at first aloof but surreptitiously watches them through their unshuttered windows. When they start to make love, he raps on the door and offers wine as a welcoming gift. Ritchie compliments the “feminine touch” within the beach house and looks askance when Timothy takes credit for a table decoration. As they toast Choke Cherry Bay, Timothy quibbles about whether Choke Cherry really is a bay, prompting Lily to try too hard to compensate for Timothy’s rudeness. After Ritchie leaves, Lily scolds Timothy for his lack of hospitality and accuses him of needing to brood. Timothy admits he has a bad feeling about their landlord, but Lily disagrees with him. When Timothy tries to drive off in anger, Ritchie’s dogs viciously circle his car, frightening him into honking until Ritchie comes out of his house to call them off. Amused by Timothy’s fear, Ritchie says condescendingly that the dogs are unfamiliar with his smell. On another day, as Lily and Ritchie walk along the beach, she explains that she met Timothy when he jumped out at her wearing a clown nose and made her laugh. Proudly, she explains that Timothy studied mime in Paris, art, photography and drawing and then, aware of Ritchie’s unspoken disapproval of Timothy, adds that she hopes the beach house will bring out Timothy’s good qualities. While talking, she strips down to her bikini in order to get a tan, embarrassing Ritchie. At her questioning, Ritchie admits that Timothy seems younger than his age, but evades answering her direct question of whether he thinks Timothy is immature. Lily points out that, while Ritchie feels certain about himself, Timothy “does not know who he is yet.” Meanwhile, as Timothy is taking photographs of himself and the area, he encounters another bay resident, an older veteran named Stanley, who simply stares at him in amusement when he tries to start a conversation. One night, Ritchie invites the couple to his house, where Lily and, especially,Timothy get inebriated. Lily asks Timothy to perform mime and his clown act. As Timothy prepares in another room, Lily, sensing Ritchie’s disdain of Timothy and wanting his respect, tentatively explains that she is more than she may seem and makes the money in their household. Ritchie interrupts, saying, “I respect you.” Timothy then bursts into the room, with his face covered in shaving cream to imitate the white makeup of a mime, and begins to perform “the definitive ape.” This disappoints Lily, who prefers his clown act, but Ritchie comments that Timothy shows more concentration when he does his ape routine than he shows in the rest of his life. He points out that gorillas are usually seen behind bars and, claiming that the experience of prison focuses a person, convinces Timothy to agree to meet him at dawn for a psychological experiment. The next morning, Ritchie wakens the hung-over Timothy and, treating him like a subordinate in the military, orders him to carry a pile of rocks to the beach. Timothy treats it as a joke, but Ritchie insists that he carry out the task. Leaving one of the dogs to guard Timothy, Ritchie proceeds to the beach house, where he wakens Lily, and stands at the door until she gets up and dresses. Then, after asking if he can “borrow” items, he walks through the rooms and gathers knives, razors, belts and other implements that could be used as weapons. Although bewildered, Lily plays along, acknowledging that they are playing a “prison game.” As Timothy continues to move the pile of rocks, Ritchie and Lily sit and watch from the beach house porch. When Timothy starts to take a break, Ritchie orders him to stand and hold a large rock, and tells Lily that Timothy is undergoing the most therapeutic experience of his life. Ritchie informs Lily that, during Revolutionary War battles, families of officers often watched from nearby. He also describes how he collected guns from the enemy corpses in Vietnam and that when he was wounded, someone stole his guns, believing he was dead. Unexpectedly, the dog attacks Timothy, causing him to bleed and, although the wound is minor, both Lily and Timothy panic. In the evening, Timothy paints, ignoring Lily, who resumes a former smoking habit. Stanley visits Ritchie, who regales him with military stories of tormenting subordinates, and their loud laughter, amplified by the water, unnerves Lily and Timothy. Later, the Frishers awaken to discover Ritchie towing away their car. When they go out to protest, the dogs threaten to attack them. During the night, Timothy tries to escape using the motorboat, forcing the frightened Lily to join him. However, the boat is cabled to the dock and Ritchie takes them back to the beach house, where he orders both dogs to guard them. That day, the Fourth of July, American Legionnaires ceremoniously present Ritchie with a flag to honor his deceased father, a colonel, as part of an annual ritual. Afterward, while Timothy continues to move the rocks, Lily goes to Ritchie’s house to talk. When she admits she is lonely, Ritchie asks if it is because of Timothy and promises that the situation will soon be different. She asks Ritchie’s opinion of her and he says she needs a man, not a boy, who will bring her “peace and pleasure” that she has never known. Lily agrees that her soul is starved and, as Ritchie confides to her a story about a little girl he knew as a child, she removes her clothing, angering Ritchie. When she begs him to let them leave, he yells at her, forcing her to retreat, naked, to the beach house. Ritchie then shouts at Timothy, who has removed his shirt in the hot sun, and tells him to put it back on and button it up. Almost incoherently, he bellows that buttons are the difference between wild savages and civilization. That night, still out of control, Ritchie prays for God to kill his enemies and burn them. He begs, “Bring fire on them!” and, as if on cue, a fireworks display commences, causing Ritchie to rejoice in sardonic glee. Meanwhile, Timothy pens up a dog and tries to barricade himself and Lily in the beach house. In retaliation, Ritchie shouts an attack command to the dogs, and while Timothy fends off one dog, Lily manages to stab it. Soon after, Ritchie gains entrance through a window, and he and Timothy fight in the dark. Their struggling ends, and Ritchie, lying on the ground exhausted, catches his breath. Near him lies Timothy, who, between bursts of fireworks, relives moments from his recent past. Shortly after, Lily announces that Timothy is dead.