The movie begins in a dimly lit garage where a teenage girl lies unconscious, her head tightly bound with duct tape and her legs chained to the rear of two cars. As the scenario unfolds, a man and a woman approach the vehicles, preparing to drive away while dragging the victim along the ground. At a critical moment, the woman notices the girl, but before she can alert the man, he accelerates, steering the cars in separate directions.
Meanwhile, Neil Conners receives an alarming anonymous chain letter via email, which warns him that he is the original link and must forward it to five individuals or face dire consequences. In an attempt to comply with the demands, his sister Rachel (Cherilyn Wilson) sends the message to only four people. Neil, determined to ensure the chain is complete, adds Rachel’s name before sending it, fulfilling the requirement.
The chain letter eventually reaches Rachel's best friend Jessica “Jessie” Campbell, who also forwards the email to five friends. However, Johnny Jones, another recipient, dismisses the letter as nonsense and chooses not to participate. Unbeknownst to him, a dark fate awaits as he is violently assaulted at the gym by a mysterious, black-hooded figure. The attacker chains him to the gym set, inflicts a grievous injury by cutting across his ankles, and ultimately takes his life.
Back at home, Rachel becomes increasingly anxious, sensing a potential intruder lurking about. In a tense series of events, she is confronted by the killer, who mercilessly whips her with a chain as she desperately tries to evade capture. In a frantic attempt to secure herself, Rachel locks the bathroom door and searches for a weapon. Unfortunately, as she desperately presses her face against the door to listen, she realizes that the killer is mimicking her actions just outside. Moments later, the killer shatters through the wall, resulting in a brutal attack where Rachel meets her end.
Outside, Jessie is approached by Detective Jim Crenshaw. He instructs her to forward the chain letter, but Jessie realizes they are being monitored through a virus embedded in the message. Concerned for their safety, she advises Neil and Michael to acquire new email addresses and phone numbers in the hope of disrupting the chain and halting the murders. Yet, as the cycle continues, Neil panics over the mounting messages and decides to erase them all. In a harrowing revelation, he confronts the killer, who has taken to the rooftop of Neil’s house, dragging him into the night with a deadly chain.
The following day, devastating news comes to light: the girl chained to the cars at the beginning of the film is indeed Jessie. Her fate is sealed as she is killed for failing to sufficiently propagate the chain letter. Despite Michael's desperate attempt to rescue her, it is too late; as her father departs the driveway, Jessie meets a horrific end, torn apart as the chain takes its toll.
As the film draws to a close, Detective Crenshaw is ominously shown chained to a table, while the menacing killer prepares a fresh batch of chains, leaving viewers in suspense of who might be the next victim in this relentless cycle of terror.
