View source for Friday the 13th (1980)

==Plot==
The film begins at Camp Crystal Lake, a summer camp for children, on Friday, June 13, 1958. It is nighttime and through the eyes of an unknown person, we watch as two teenage counselors sneak away from a campfire sing-along to have sex in a nearby barn. The two counselors, Barry and Claudette, are surprised by the unknown person and the person proceeds to murder Barry. Claudette tries to flee but is eventually cornered and murdered.

Twenty-two years later, in 1980, the camp is being reopened after being shut down for the murders of the two counselors by a man named Steve Christy. One of Christy's newly hired counselors, Annie, decides to hitchhike to Camp Crystal Lake. She manages to hitch a ride with a truck driver named Enos, but before leaving she encounters the town crazy, Ralph, who warns her that Camp Crystal Lake has a death curse. While driving with Enos, he also warns her about the camp and tells her about a boy that drowned in Crystal Lake and the two counselors that were murdered. Annie dismisses these warnings and continues to Crystal Lake, only to then hitch a ride from an unseen stranger who proceeds to chase her into the woods and murder her by slashing her throat.

Three of Christy's newly-hired counselors, Ned, Jack, and Marcie arrive at the camp and meet Mr. Christy, as well as a few other counselors; Bill, Brenda, and Alice. They all begin refurbishing and setting up the camp without Annie.

After a while, Mr. Christy heads into town leaving the six teens to finish their tasks. They eventually take a break and go swimming, where an unseen prowler watches them from the other side of the lake. Ned, the jokester of the bunch, pretends to drown only to get mouth-to-mouth from Brenda.

The counselors start making lunch for themselves when a police officer arrives at the camp to warn about Ralph, the town crazy, and soon after he leaves, Ralph surprises Alice in the main cabin and warns her and the other counselors about the camp's death curse.

As night begins to fall and as a thunderstorm rolls in, Ned wanders off down the lake and sees someone lurking in one of the cabins and investigates. Jack and Marcie enter the same cabin to seek shelter from the incoming storm and have sex, unaware that Ned is lying on the top bunk above them with his throat slashed. Alice, Bill, and Brenda smoke pot and play strip Monopoly in the main cabin. Marcie and Jack finish and Marcie leaves to use the bathhouse. Ned's blood drips down onto Jack from the top bunk but before Jack can investigate, he is murdered by an arrow through his neck from underneath the bed. The killer then follows Marcie to the bathhouses where she is too murdered with an axe to the face.

The rain has picked up and Brenda leaves Bill and Alice to close the windows in her cabin. Meanwhile, Steve Christy finishes up in town, stopping at a local diner and then heads back to the camp only for his car to break down. He hitches a ride from a police officer, Sgt. Tierney, and is given a lift to the camp. Upon arrival, Steve Christy encounters someone flashing a light in his face. He soon recognizes this person and is then stabbed in the stomach by the unseen killer.

Back at camp, Brenda is lured out of her cabin by a strange, child-like voice to the archery range, where she is seemingly murdered. Her screams send Bill and Alice searching for Brenda and the others, but to no avail. They try to use the phones and the vehicles to discover none of them are working. The two decide to wait it out for Mr. Christy and Alice falls asleep in the main cabin. Bill leaves to check the generator in the shed. Alice wakes up and leaves to find him and when she reaches the generator shed, she discovers Bill, dead, pinned to the door of the shed with multiple arrows. Screaming, Alice runs back to the main cabin, barricading herself inside and arming herself. After it gets quiet, Brenda's body is hurled through the window at Alice, and headlights appear outside. Fleeing from the body, Alice runs outside, thinking the headlights belong to Steve's Jeep, but a woman named Pamela Voorhees steps out of the vehicle.

Alice shows Mrs. Voorhees the carnage and Mrs. Voorhees begins to comfort Alice, but eventually begins raving about a young boy that drowned in 1957. She explains that the boy's name was Jason and he was her son, and Friday the 13th is his birthday. Mrs. Voorhees becomes aggressive and proceeds to reveal herself as the killer, seeking revenge on the counselors who let Jason drown by not watching him, charging at Alice. Alice manages to fend off the crazed killer with a fireplace poker and flees, discovering Annie's body in Mrs. Voorhees's Jeep and Steve's body hanging from a tree.

Alice runs to the boathouse where she finds a gun, but can't find any bullets. Mrs. Voorhees enters the boathouse and overpowers Alice before Alice manages to strike her with the gun and flee once again. She runs back to the main cabin and hides in a closet. After a few moments of quiet, Mrs. Voorhees appears again and begins chopping through the door. She breaks inside and Alice manages to hit her with a frying pan, knocking her unconscious. Alice, believing her to be dead, stumbles down to the lake and falls onto the shore, exhausted. But it isn't long until the crazed Mrs. Voorhees attacks again. After a prolonged struggle, Alice manages to grab Mrs. Voorhees's machete and decapitate her.

Traumatized, Alice climbs into a canoe and floats out into the middle of the lake. When daylight comes, she sees police officers on the shore of the lake but before she can call to them, the decomposed body of young Jason Voorhees comes lunging out of the water, grabbing Alice and pulling her out of the canoe. Alice wakes up in a hospital and tries to explain to the police officer that there was a boy in the lake, but the officer claims they didn't find a boy. The film ends with Alice saying "Then he's still there" with a lingering shot of the lake.