In a chilling prologue set in 1958, two counselors at Camp Crystal Lake, Barry and Claudette, sneak away from a campfire sing-along for a moment of intimacy. However, their romantic interlude takes a terrifying turn as an unseen assailant intrudes upon them, leading to their brutal murders.
Fast forward to Friday, June 13th, where a young woman named Annie walks into a small diner seeking directions to Camp Crystal Lake. Her inquiry raises alarms among the diner’s patrons, especially a peculiar old man named Ralph, who ominously warns her, saying they are “all doomed.” A friendly truck driver named Enos offers to give Annie a ride halfway to the camp. During their journey, he recounts the tragic incident of a boy who drowned in the lake back in 1957, the same year as the grisly double murder of the two counselors. After being dropped off, Annie continues her trek but is soon picked up by an unseen driver in a Jeep. As they pass by the camp entrance, Annie becomes anxious and hastily jumps from the moving vehicle, only to be pursued into the woods by her mysterious assailant, who fatally wounds her with a bowie knife.
At camp, the other counselors—including Ned, Jack, Bill, Marcie, Alice, and Brenda—are busy refurbishing the cabins under the watchful eye of their demanding head, Steve Christy. Their time together is punctuated by strange occurrences, such as a prank involving a fake drowning and an alarming snake discovery, which they eliminate with a machete. Once again, Ralph arrives to repeat his eerie warnings, heightening the sense of foreboding around the camp.
With a violent storm approaching, Steve leaves to gather supplies, unaware of the danger lurking in the shadows. The unidentified killer begins methodically isolating and dispatching the counselors one by one. As the storm rages outside, Marcie and Jack seek shelter in a cabin for a rendezvous, completely oblivious to the fact that Ned’s lifeless body occupies the upper berth. Shortly after their encounter, Jack meets a grim fate when an arrow pierces his throat from beneath the bed. Meanwhile, Marcie hears strange noises in the bathroom, and as she investigates, she encounters the killer, who brutally ends her life.
As the night drags on, Brenda is lured outside by a mysterious child-like voice calling for help. She ventures out into the pouring rain only to fall victim to the hooded killer. In a state of panic, Bill and Alice begin to search for their missing friends, only to stumble upon a bloody axe in Brenda's bed, confirming their worst fears of foul play. Their attempts to contact the police are thwarted when they discover the phone lines have been cut and their vehicles won’t start.
Meanwhile, Steve faces his own peril as he struggles to return to the camp after dinner. Stuck in mud, he finds a temporary ride but is soon met with tragedy as he is murdered by someone he seems to recognize upon his return.
When the camp’s lights extinguish, Alice bravely seeks out the power generator but finds it malfunctioned and discovers Bill's body pinned to a door. Alone and terrified, she finds herself barricaded as Brenda’s corpse is suddenly thrown through a window, escalating the horror that surrounds her. Hearing a vehicle, Alice rushes outside only to meet Mrs. Voorhees (Betsy Palmer), who identifies herself as an “old friend of the Christys.” While Alice tries to explain the gruesome events, Mrs. Voorhees chillingly reveals that she is the mother of Jason, the boy who drowned.
Fueled by madness, she blames the counselors for her son’s death, believing their negligence led to his drowning. During a tense confrontation, Mrs. Voorhees pulls out her bowie knife and attacks Alice, who manages to temporarily subdue her. A heart-pounding chase ensues through the camp as Alice discovers the gruesome fates of other counselors. Armed with a rifle, she faces her tormentor until ultimately dispatching Mrs. Voorhees in a desperate battle by decapitating her.
In a daze, Alice drifts out into the lake in a canoe, seeking solace. However, her rest is abruptly disturbed when the decomposing body of Jason pulls her underwater just as she wakes up in a hospital. A police officer informs her of the grim outcome at the camp, but when she inquires about Jason, the officer reveals they never found him. Realizing the horror isn’t truly over, she ominously concludes, “Then he’s still there.”
