One year after the conclusion of the last film (Part 7), a boat's anchor hits an underwater power line cable, causing a short circuit at the bottom of Crystal Lake. As a result, the undead serial killer Jason Voorhees (Kane Hodder) is resurrected once again. He immediately finds the boat's occupants, a high school couple named Jim Miller (Todd Shaffer) and Suzie Donaldson (Tiffany Paulsen), having sex. Obtaining a new hockey mask from the boat (which Jim had previously used to scare Suzie), he kills Jim with the barrel of a harpoon gun. Suzie attempts to hide in a storage hatch, but Jason discovers her and jams the harpoon into her chest.The next morning, the steamer SS Lazarus, containing the senior class of Lakeview High, is bound for nearby New York City for the school's graduation. The trip is chaperoned by Colleen Van Deusen (Barbara Bingham) and biology teacher Charles McCulloch (Peter Mark Richman), who has also brought along his niece, Rennie (Jensen Daggett). Before the ship sets sail, Jason (having somehow sailed Jim and Suzie's boat to the marina) grabs a hold of the ship's anchor and climbs aboard.As the night continues on, Rennie keeps having visions of Jason as a child (Timothy Burr Mirkovich) when he drowned. Jason then starts murdering the people on board, starting with a wannabe rock star named J.J. (Saffron Henderson), whom he kills by bashing her head with her own electric guitar. He then ambushes a young boxer in a sauna and hits him with a sauna rock in his chest.Tamara Mason (Sharlene Martin) goes to take a shower. Jason breaks through the door and strips Tamara, leaving her completely naked. She begs for mercy and tries to hide her nakedness with a bathroom towel as Jason shatters the bathroom mirror and impales her with a broken glass shard. Her dead body is later discovered lying on the floor.Jason then kills the captain of the Lazarus, Admiral Robertson (Warren Munson) and the chief engineer Jim Carlson (Fred Henderson), leaving the two chaperones, Rennie, and the remaining students to try and track down and kill Jason. They fail, after Jason strangles one of the female students, Eva Watanabe (Kelly Hu), on a dance floor, then throws one boy, Miles Wolfe (Gordon Currie), over the captain's quarters and onto the deck post. However, Wayne's death, involving being thrown into a control panel, causes a fire, burning the fuel tanks, and blowing a hole in the ship's hull.Jason then comes extremely close to killing Rennie by almost choking her to death as his bursts his decomposing arm through a porthole. She then manages to stick a pen up his left eye. Then Charles, Rennie, Colleen, two other students, Julius (V.C. Dupree) and the captain's son, Sean Robertson (Scott Reeves), and Rennie's dog, Toby (Ace), abandon the ship in a lifeboat as the ship continues to burn with the remaining students onboard.As the group continues to row to safety, they finally arrive in New York City. Jason has followed them there, however, and kills two gang-bangers. Jason then kills Julius (decapitated by a single punch), then a cop (Roger Barnes) the group comes across. Colleen is killed accidentally when immolated in an exploding car. Finally, Charles is caught by Jason and dunked in a barrel of sewage, leaving Sean and Rennie running for their lives. Rennie has a flashback to an event from her early childhood where she was learning how to swim in Crystal Lake and was almost killed by a young drowned Jason, looking as he did in the original Friday the 13th.The infuriated Jason is now on the warpath and after a chase that spans from the subway system to Times Square, Rennie and Sean first run into a diner, followed by the sewers of Manhattan, where Jason follows and kills a sanitation worker (David Longworth). Rennie and Sean try to escape from the tunnel by climbing up a metal ladder just as a flood of toxic waste races through the tunnel. Rennie manages to knock the persuing Jason off the ladder and whom lands in the toxic waste. Much of Jason's body melts; all that is left is a young boy lying at the bottom of the sewer. Rennie and Sean reunite with the dog Toby on the streets above.