The film opens by showing the final scenes of the previous film, Friday the 13th Part 2. Ginny Field is running through the woods when she comes across a seemingly abandoned shack. Upon entering, she sees that Jason Voorhees is stalking her, so she barricades herself inside. While Jason is trying to break through the door, Ginny discovers that the shack contains a makeshift shrine with the head and sweater of Mrs. Voorhees. In an act of desperation, Ginny puts on the sweater and pretends to be Jason's mother, telling him he has done his job well. The distraction works well enough to give Paul an opportunity to catch and struggle with the killer. While they are fighting, Ginny takes the opportunity to drive a machete into Jason's back. The couple leave the cabin and we discover that Jason is still alive.
The next scene is outside a diner near Crystal Lake, hours after the end of the previous film. A housewife, Edna, is watching a news report about the killing spree, when she notices someone walking around outside of her home. Believing it is her husband avoiding his chores, she goes outside to collect the laundry from the clothesline. Her husband, Harold, is actually in the restroom sneaking a drink when he notices a curtain move. He goes over to investigate, but finds nothing out of the ordinary. Not satisfied, he continues to search the room and when he opens a closet door, Jason plunges a meat cleaver into his chest. Edna hears a commotion and goes out to investigate, where Jason grabs her and plunges a knitting needle through her chest.
In the next scene, Shelly, Andy, Chris, and stop to pick Vera for the trip to the country for the weekend. Shelly has been set up with Vera, although she doesn't appear to be very excited when she meets him.
Body Count: 12
1. Harold: Meat cleaver to chest. 2. Edna: Knitting needle through chest. 3. Fox: Impaled with a pitchfork in the throat 4. Loco: Impaled with a pitchfork in the stomach 5. Vera: Shot in the eye with a harpoon gun 6. Andy: Sliced in half with machete 7. Debbie: Stabbed in the back 8. Shelly: Throat slashed, presumably with a machete 9. Chuck: Eletrocuted by fuse box 10: Chili: Impaled with a fire poker in the stomach 11. Rick: Head is crushed, bare-handed 12. Ali: Hacked to pieces with a machete