The Tommyknockers

Gard has a metal plate in his head from a previous skiing accident. Bobbi suspects this metal implant is muting whatever alien improvement is affecting the rest of Haven. This metal plate acts as a barrier against the telepathic and transformative effects of the buried alien object, allowing Gard to remain mostly unchanged while other residents succumb to the influence.

Earlier in the film, Bobbi wonders if Gard's head plate might be inhibiting whatever is changing the town.

Davey was taken into the alien spacecraft buried beneath Haven. When Hilly used his 'magic machine' on Davey in an attempt to bring him back, the ritual backfired and Davey vanished, transported inside the ship. He was trapped in a glowing green crystal, being used as the ship's power source, draining his life force to fuel the alien vessel.

Ev Hillman tells Gard that Davey is 'with the tommyknockers' while they are trapped in the garage.

The tommyknockers are the alien beings buried beneath Haven. The term originates from mining folklore, knocking sounds miners heard were supposedly spirits warning of danger. In the movie, Deputy Becka Paulson mutters this cryptic phrase after witnessing her husband's electrocution, and it becomes clear the aliens have been influencing the town for centuries, with newspaper articles dating back two centuries documenting mass murders and deadly accidents linked to the area.

Ev researches Haven's history and finds newspaper articles from two centuries ago about mass murders and hunting accidents connected to the cursed area.

Bobbi admits she experimented on her own dog Peter before the alien influence fully took hold. This confession is significant because it reveals her responsibility for the chain of events that led to Davey's danger, when the alien ship began absorbing life force, it pulled in the energy of those closest to the artifact, and Peter was among them. The guilt and emotional flood of this confession breaks the ship's mental hold on Bobbi, allowing her to resist its control and help free Davey.

Throughout the film, Peter the dog is shown watching the excavations and later appears encased in green crystals alongside the other victims.

The buried alien starship was powered by human mental energy. Davey, trapped in a crystal inside the ship, served as the primary power source, and the ship's systems were also siphoning life force from Bobbi and other townspeople who had been 'converted.' The green glow that appeared when gadgets were activated was the visible manifestation of this energy transfer, which drained the townspeople's vitality and caused their physical decline.

The townspeople's energy drains as they become more obsessed with their inventions, and Gard notices their hair falling out and pale skin.

The alien artifact was subtly influencing the townspeople's minds, enhancing their creativity and technical abilities while simultaneously draining their energy. The green-powered gadgets represented the 'improvement' the alien influence was creating in Haven's residents. This telepathic control made them compulsive about building and using these devices, even as their health deteriorated, the transformation was both appealing and destructive.

As soon as Bobbi and Gard uncover more of the artifact, the town begins inventing odd gadgets that glow green when activated.

Gard removed one of his teeth to prove his loyalty to the faction and convince Bobbi that he was genuinely committing to 'becoming' with the others. This extreme act was a calculated deception, he was feigning allegiance so he could infiltrate the group and find Davey. By removing a tooth, he demonstrated the kind of painful commitment the converted townspeople expected, allowing him to gain access to the locked garage and discover where Davey was being held.

Gard tells Bobbi they must descend into the alien object to 'become' completely, convincing her of his commitment.

After Bobbi's confession broke the ship's mental hold, Gard connected himself to the ship's control panel while Bobbi freed Davey from his crystal prison. They ascended to the surface through the portal. Once outside, Bobbi and Davey fled into the woods while Gard stayed attached to the vessel, piloting it upward before detonating it. Gard destroyed the ship to prevent the aliens from reanimating and to stop the ongoing threat to Haven.

Bobbi's emotional confession occurs during the crisis inside the ship, breaking the alien control that had prevented any resistance.

The alien spacecraft had been dormant for centuries and required human mental energy to reactivate. Davey, as a child with strong psychic potential, became the ideal power source. The ship's telepathic link to the alien pilot meant it could only be controlled through mental energy, and when the alien died, the ship needed a human substitute to function, the life force drain was essentially the ship recharging itself using human minds.

The alien pilot is found strapped to a massive wheel-like device, indicating the ship was designed to be controlled through mental connection.

Ev Hillman choked Nancy Voss to death after Nancy tried to kill Bobbi and Davey with her lipstick disintegrator ray. When Nancy shot and killed Bryant Brown in a failed attempt to destroy the ship's hull, she became violently unstable. Ev, still partially conscious and connected to the alien energy, intervened to protect Bobbi and Davey, strangling Nancy before dying himself from his injuries. This act was one of the many violent confrontations during the chaotic climax.

Nancy becomes increasingly erratic, using her disintegrator ray on the troopers earlier and showing no hesitation in using lethal force.

The explosion destroyed the alien spacecraft and killed many of Haven's remaining residents, including Gard. The strange inventions and green glow faded as the source of the alien influence was eliminated. The town was left to reckon with the devastation, many lives were lost, and the survivors had to process the traumatic events. Bobbi mourns Gard's sacrifice, which saved the town from the immediate threat but came at a tremendous human cost.

The climax shows multiple casualties as the town collapses into chaos during the confrontation at the excavation site.

Gard sacrificed himself because he was the only one who could pilot the alien vessel away from Haven and destroy it before the aliens could reanimate. With the alien pilot dead, the ship needed a human mind to control it. Gard connected himself to the vessel, lifted it into the sky, and detonated it, ensuring the threat was eliminated completely. His sacrifice saved Bobbi and Davey, prevented the aliens from returning, and ended the energy drain on the town.

Gard tells Bobbi and Davey to leave while he handles the ship, indicating he plans to do something drastic.