As the sun sets over Crystal Lake, Jim Miller captivates his girlfriend Suzi with the chilling lore of Jason Voorhees. In a light-hearted moment, he decides to surprise her by donning a hockey mask and wielding a prop knife, intending to scare her away. However, unbeknownst to him, their houseboat’s anchor has disrupted some submerged cables, inadvertently reviving the dormant corpse of Jason, who was believed to be dead from the previous encounter. With a thirst for vengeance reignited, Jason seizes this eerie moment to reclaim his notorious mask and unleash a horrific reprisal, culminating in Suzi's shocking harpooning.
The following morning, the SS Lazarus embarks for New York City, carrying a group of students from Lakeview High School on their graduation trip. Among the chaperons are biology teacher Dr. Charles McCulloch and English teacher Colleen Van Deusen, both of whom unexpectedly find themselves accompanied by Van Deusen's niece Rennie. McCulloch is clearly strained by the presence of his niece, who has an intense fear of water. Unbeknownst to the entire group, Jason has stealthily boarded the vessel, lying in wait for his next unsuspecting prey. His first victim is the aspiring rock star J.J. Jarrett, whom he swiftly dispatches using her own guitar.
As darkness engulfs the SS Lazarus, Rennie’s world takes a darker turn when she encounters a young boxer recently defeated by champion Julius Gaw in the sauna, resulting in a chilling confrontation with Jason, who swiftly claims another life. Rennie, still reeling from a previous encounter involving her pet Toby, sets off to find her dog, only to stumble upon prom queen Tamara Mason and her friend Eva Watanabe partaking in clandestine activities. However, Tamara mistakenly believes Rennie has exposed their secret and pushes her overboard in retaliation. Later in the evening, as Tamara seeks refuge in a shower after rejecting Wayne Webber’s advances, she finds her peace shattered when Jason appears in the bathroom, ending her life with a shard of glass.
As the ship’s environment becomes increasingly fraught, a sense of foreboding envelops the passengers. Rennie begins to suffer from unsettling visions of a young Jason, haunting her throughout the SS Lazarus. One by one, the lives of students, including J.J. Jarrett and Julius Gaw, are brutally claimed by Jason, leaving behind chaos and terror. Eva discovers Tamara's lifeless body and tries to escape, only to meet a gruesome fate herself in the disco room.
As surviving students band together, McCulloch remains adamant that the ship’s deckhand is the source of their troubles. However, that theory rapidly crumbles as the deckhand is soon found a victim of Jason. A horrific incident in the radio transmitter tower claims Miles Wolfe, and as Rennie, McCulloch, Van Deusen, and Sean Robertson (the captain's son) manage a narrow escape via a life raft, they spot survivors among their ranks—Toby and Julius.
Navigating through the one-way concrete jungle of New York City, the relentless pursuit of Jason wreaks havoc on the streets. In a harrowing moment, Rennie finds herself at the mercy of drug addicts, who ultimately abandon her, leaving her to fend for herself. While they scatter in search of help, Julius’s brave confrontation against Jason leads to his untimely demise, falling victim to exhaustion in a grave showdown.
Rennie stumbles into Sean and the teachers, finding brief solace with the NYPD’s assistance. Yet, their safety nets disintegrate when Jason mercilessly eliminates the officer trying to help. As her grip on reality tightens, Rennie experiences hallucinations of Jason, culminating in an adrenaline-fueled moment where she crashes a police cruiser, resulting in a massive explosion that engulfs Van Deusen in flames. The chaos unveils McCulloch's haunted past with Rennie, rooted in her fear of water stemming from a childhood trauma.
In a desperate escape, Rennie and Sean flee, pursued by the relentless Jason, which leads them into the bowels of the subway system. In a moment of courage, Sean incapacitates Jason, sending him crashing onto electrified tracks. While they seek safety through the vibrant lights of Times Square and a dingy diner, they encounter a foreboding warning from an underground worker that the sewers are set for flooding with toxic waste.
Jason resurfaces, brutally taking down the worker and leaving Sean reeling. Rennie, in a decisive maneuver, splashes Jason with a toxic substance. Their tense climb up a precarious ladder exposes them to the flooding sewers, where Jason is gripped by the haunting memory of his childhood trauma. The floodwaters ultimately disintegrate his form, leaving behind a haunting image of a young boy, likely Jason himself.
As the chaos finally settles, Sean and Rennie emerge, reuniting with Toby amidst the stunning lights of Times Square, bringing a surreal close to their harrowing ordeal.
