Twenty years after a series of mishaps, careless disastors, and a grizzly, unsolved double homicide, Camp Crystal Lake, known nefariously about town as Camp Blood, is being re-opened by its new owner, Steve Christy (Peter Brouwer), and seven young counselors.

Despite apprehension by local residents and warnings of a "death curse" by the town loony, Crazy Ralph (Walt Gorney), Christy and his assembled entourage begin readying the property for a re-opening on, of all days, Friday the thirteenth.

As nightfall looms and a thunderous rainstorm erupts overhead, the counselors begin to fall prey to an unseeen prowler one-by-one until only Alice (Adrienne King), the shy, introverted artist who considering returning home early in the film, is left alone.

It is then that we learn that Mrs. Voorhees (Betsy Palmer), a former cook at the camp, is the one behind the knife. Two decades prior her son, Jason, drowned in the lake while the counselors sat idly by. Now she is taking her revenge.

The film climaxes with a hasty cat-and-mouse between Alice and the revenge-stricken mother, eventually winding up on the lake's beach where Alice, after being viciously beaten, beheads the insane women with a machete. A harrowing final nightmare sequence suggests that Jason is still alive and enraged over his mother's death.

The film was shot on a budget of $500,000 during the Summer of 1979 at Camp NoBeBoSo in Freehold, New Jersey. It was released theatrically on June 13, 1980 (the same day as Stanley Kubrick's The Shining) and went on to become the surprise box office hit of the Summer, grossing close to $40 million. Sean S. Cunningham, the director, had made his first foray into the motion picture world six years earlier as a co-producer on Wes Craven's infamous exploitation chiller Last House On The Left.