Eight years ago, Angela survived a boating accident that killed her father, John, and her brother, Peter. Afterward, she was sent to live with her eccentric Aunt Martha and Martha’s son, Ricky. Angela is now a young teenager, and one summer Aunt Martha sends her and Ricky to Camp Arawak, located on the same upstate New York lake where the boating accident occurred. Ricky has previously attended the co-ed camp, but the visit marks the first time for Angela, who is extremely introverted. After arriving by bus, Ricky gives Angela a tour and tries to introduce her to Judy, a camper Ricky dated last summer, but the snobby girl ignores the cousins. As Angela settles into her assigned cabin, she does not talk to the other girls. After three days, she remains silent, and Ronnie, the lead camp counselor, is also concerned that Angela has not touched her food. He takes her to the kitchen and asks Artie, the head chef, to find something she might like to eat. Meanwhile, Ricky, who is very protective of his cousin, defends Angela, as Judy and other cabin mates poke fun at her. When Ricky wanders into the kitchen pantry to look for Angela, he catches Artie about to molest her. Artie threatens Ricky if he speaks about the episode. Later, as Artie stands over a large pot boiling on the stove, someone spills the scalding water on him, burning his face and body. While the ambulance takes Artie away, Mel, the director of Camp Arawak, does not want to upset the campers and urges Ronnie to keep the incident quiet. At the recreation center, two campers named Kenny and Mike tease the uncommunicative Angela as she sits by herself. Ricky arrives and orders the boys to leave his cousin alone, inciting a fight. Afterward, Paul, Ricky’s best friend, comforts the nearly catatonic Angela by offering his condolences for her family’s accident. The young girl finally speaks when she tells Paul, “goodnight.” At the lake later that night, Kenny smokes marijuana with Mike, then persuades Leslie, a fellow camper, to join him on a canoe ride. When Kenny flips over the boat as a prank, Leslie swims to shore while Kenny, under the influence of the marijuana, enjoys the airspace beneath the overturned canoe. Suddenly, another person appears and drowns Kenny. A counselor finds the dead body the next morning. Concerned about the reputation of the camp, Mel is anxious for police to report the drowning as an accident, but Ronnie informs an officer that Kenny was a good swimmer. Meanwhile, the scheming Judy watches as Paul flirts with Angela. After a movie screening at the recreation center, Angela is surprised when Paul gives her a chaste kiss, and she runs away. The next day, Meg, one of the female counselors, pesters Angela for not swimming in the lake with the rest of the campers and begins shaking the silent girl. Judy taunts Angela for not taking showers with the other girls. After an arrogant camper named Billy and his friends throw a water balloon at her, Ricky defends his cousin, screaming obscenities at the bullies, until camp director Mel intervenes. When Billy goes to the bathroom, someone barricades the stall and throws an active beehive at him. Billy collapses and dies as bees swarm over his body. After the corpse is discovered, Mel tells Ronnie the camp’s reputation has been ruined, but he has an idea who is responsible for the killings. Meanwhile, Angela feels more comfortable with Paul and kisses him at the beach by the lake. While they are lying on the sand, Angela remembers a moment in her childhood when she watched her father having sex with another man. Suddenly, she pushes Paul away and leaves. The next day, Paul is frustrated when Angela tells him she is not ready to be intimate. Seizing the opportunity to steal Angela’s new boyfriend, Judy lures Paul to a secluded spot. As Angela walks in the woods, she encounters the two kissing and becomes upset. Paul tries to apologize the next day, but Judy interrupts and tells Angela Paul called her a “prude.” When Paul walks away, Judy and Meg throw Angela into the lake. Nearby, Mel accuses the tempestuous Ricky of being the killer. Ricky breaks free of Mel and runs to help Angela. That night, Meg arranges a secret date with Mel, but she is stabbed while taking a shower in one of the cabins. When Mel finds Meg’s body, he vows to avenge her death by apprehending Ricky. Meanwhile, Judy is alone in a cabin styling her hair when the killer appears and murders her with the hot curling iron. Mel finds Ricky walking alone and beats him, while the boy denies hurting anyone. As the director leaves Ricky lying unconscious on the ground, the actual camp killer appears and shoots an arrow through Mel’s throat. Police arrive at the gruesome scene, and Ronnie alerts the counselors there is a killer on the loose. At the lake, Angela arranges a rendezvous with Paul. She appears to forgive him for flirting with Judy and suggests they go skinny-dipping, but she drowns the boy. Afterward, she thinks back to when she moved in with Aunt Martha eight years before. At the time, “she” was a boy, because the child who survived the boating accident was not Angela, but her brother Peter. Since Aunt Martha always wanted a little girl, she decided to raise Peter as female and call him “Angela.” At the lake, Ronnie and another counselor encounter “Angela” standing naked over Paul’s body, and are shocked that the shy camper is actually a boy, who has become a diabolical killer.