Bobbi Anderson, Marg Helgenberger, a Western fiction writer, and her boyfriend Jim 'Gard' Gardner, Jimmy Smits, a poet, live with their dog Peter on the outskirts of Haven, Maine. Bobbi wrestles with writer's block while Gard—an recovering alcoholic who isn’t writing at the moment—tries to make sense of a life that feels stalled. One day, Bobbi stumbles upon a manmade stone object protruding from the ground. She shows Gard and they begin to excavate the artifact, uncovering a series of connected cubes crafted from an unknown alloy. As they peel back the layers of the object, Haven begins to shift in unsettling ways: insomnia settles in, a rudimentary telepathy threads through conversations, and some residents start tinkering with odd gadgets assembled from kitchen tools, batteries, small appliances, and other odds and ends. The devices glow a vivid green whenever they’re activated, casting an eerie light over the town.
Gard is stunned when Bobbi’s telepathic typewriter suddenly conjures a sharply written novel about buffalo soldiers, while Bobbi herself digs compulsively around the artifact, revealing more and more of its hidden depths. Gard bears a physical reminder of his past—a metal plate in his head from a skiing accident—and Bobbi wonders if that implant might be muting whatever is “improving” the rest of Haven. The changes don’t stop with the adults; even the children begin to show strange signs. A child named Hilly Brown, Leon Woods, uses his “magic machine” on his brother Davey Brown, Paul McIver, and Davey vanishes before their eyes. The town’s crisis begins to crystallize around this disappearance, and Sheriff Merrill, Joanna Cassidy, leads a widespread, but ultimately unsuccessful, search for the boy.
As the search drags on, the town tightens its grip on the strange new inventions that now seem to drain people’s energy. Davey’s parents—Bryant Brown, Robert Carradine, and Marie Brown, Annie Corley—grow more obsessed with their gadgets, their vitality ebbing away as the mystery deepens. Deputy Becka Paulson, Allyce Beasley, is hospitalized after witnessing her cheating husband Joe Paulson, Cliff DeYoung, electrocuted, and she begins to mutter in cryptic phrases about the “tommyknockers.” The town’s grip tightens as fear, fatigue, and fascination with the alien technology spread.
Merrill continues the search and discovers Bobbi actively unearthing the enormous object. In a tense moment, the sheriff attempts to call Trooper Duggan, John Ashton, only to be overwhelmed—assaulted by dolls and knocked unconscious. The phone lines go dead, and Duggan, along with two other troopers, ventures into the danger. Duggan is abruptly jolted by the sight of the townspeople’s apathy and illness—hair falling out, pale skin, heavy fatigue—and he flees when he feels a wave of nausea, discovering the malady recedes as soon as he leaves the vicinity. The other troopers are pulled into the town’s peril when Nancy Voss, Traci Lords, wields a disintegrator ray housed in a lipstick, its green glow destroying whatever it touches.
Gard begins to piece together what Havens’ residents are facing. He finds Bobbi standing with the others in front of the town hall, seemingly under a shared, malevolent influence, and realizes that the townspeople’s “becoming” is part of a larger mechanism. He becomes determined to escape, but his vehicle is disabled and a green energy barrier—harmful to Gard’s metal head—prevents him from fleeing. The tragedy deepens: Trooper Duggan is killed by the blast from a vending machine, and Ev Hillman, E.G. Marshall, lures Bryant and Marie into Bobbi’s padlocked garage. Gard, desperate to understand what’s happening, seizes Bobbi’s key, enters the locked space, and discovers a trove of alien technology. Inside, he finds Peter the dog, Sheriff Merrill, and Ev encased in glowing green crystals, all being used to power the alien apparatus.
Ev, still alive in a limited way, tells Gard that Davey is “with the tommyknockers,” guiding him to believe the child lies inside the buried object. To save Davey—and perhaps to save the town from itself—Gard pretends to join the group, even going so far as to remove a tooth to commit fully to the ruse. He convinces Bobbi that they must descend into the alien object to “become” completely. They discover a portal that drops them hundreds of feet into what is clearly an alien starship. Inside, they encounter a number of mummified aliens and an alien strapped to a massive wheel-like device. The ship’s control appears to be telepathically linked to the alien, and once the minds are connected, separation seems impossible. They learn that the ship is siphoning the mental energy of Davey, who is trapped in a crystal, as its power source, and that this energy drain is also feeding off Bobbi and the others’ life forces.
The revelation shatters Bobbi’s resolve: she admits that she once experimented on her own dog, and the truth: she has been indirectly responsible for the boy’s peril. The flood of emotion breaks the ship’s mental hold on Bobbi, and she and Gard free Davey and pull him to the surface. Gard pulls the dead pilot from the ship’s control panel and attaches himself to the vessel, becoming a conduit for a final act of defiance. On the surface, the town’s people realize the ship is awakening again and rush toward the excavation site. Bobbi and Davey emerge from the ship and vanish into the woods as Gard—their sacrifice a quiet counterpoint to the town’s fevered progress—drives the ship higher into the sky and detonates it, destroying the alien craft just as it seems to reanimate. The explosion and the chaos it unleashes claim several lives among Haven’s residents, and the scene closes with Bobbi mourning Gard’s sacrifice.
In the end, Haven is left to reckon with the consequences of the strange encounter, the limits of human curiosity, and the quiet courage of a man who chose to sacrifice himself to save others. The town’s strange inventions fade into memory, but the haunting image of the green glow and the price of discovery linger as a reminder of what can happen when curiosity and danger collide.
