Halloween III: Season of the Witch

Harry Grimbridge discovered the truth about Silver Shamrock's deadly plan with the Stonehenge masks. He stole a jack-o-lantern mask as evidence and was pursued by Cochran's agents to prevent him from exposing the conspiracy. He managed to reach Walter Jones's shop before collapsing from his injuries.

Each mask contains a microchip embedded with fragments of Stonehenge. When activated by the specific frequency of the 'Big Giveaway' commercial, the microchips release a combination of lethal insects, snakes, and energy beams that cause fatal brain damage. Children wearing the masks during the broadcast suffer gruesome deaths.

Earlier, Marge Guttman dies horribly after a microchip in a medallion activates, foreshadowing the mass activation via television.

Samhain is an ancient Celtic pagan festival marking the arrival of winter, traditionally associated with supernatural forces and ritual sacrifice. Cochran is a fanatical follower of ancient Celtic beliefs who intends to use the masks to sacrifice thousands of children during Samhain, believing it will restore the old ways and bring power to those who embrace the darkness.

Cochran created a synthetic duplicate of Ellie Grimbridge to infiltrate the investigation and manipulate Dr. Challis. After capturing the real Ellie, Cochran used his technology to build a perfect android copy that would lead Challis deeper into his trap. The android appears completely human until Challis discovers the truth during their escape.

When the Silver Shamrock 'Big Giveaway' commercial broadcasts, it sends a specific electronic signal that activates the microchips in all the masks worn by children across the country. This triggers the deadly payload embedded in each mask. The commercial appears innocent, featuring a countdown and the phrase 'It's Magic Time,' tricking parents into letting their children watch and wear the masks.

Stonehenge is a prehistoric stone circle associated with ancient pagan rituals, particularly those tied to solstices and Samhain. Cochran harvested fragments of the actual Stonehenge stones and embedded them in each mask. These stones serve as the conduit for the supernatural element of his ritual, channeling the dark energy needed to perform the mass sacrifice during Samhain.

Dr. Challis rushes to Walter Jones's shop and desperately calls television stations, begging them to pull the commercial. He successfully convinces two stations to stop airing it, but his final plea to a third station fails. The broadcast goes out, and many children are affected by the deadly masks, though the exact death toll is unknown.

The attacker is one of Cochran's agents sent to eliminate Harry Grimbridge at the hospital. Rather than be captured, he chooses to set himself on fire, possibly as a failsafe mechanism or ritualistic act tied to Cochran's pagan beliefs. This self-immolation ensures he cannot reveal any information about Silver Shamrock or Cochran's plans.

Marge Guttman discovers a microchip hidden inside a medallion while adjusting her hair at the Santa Mira motel. The microchip activates from her movements and releases a deadly energy beam that grotesquely disfigures her. An insect then crawls from her mouth, killing her. This is a 'misfire' of the technology that Silver Shamrock later uses in the mass attack.

This incident demonstrates how the microchips work before the main attack occurs.

Silver Shamrock Novelties appears to be a legitimate Halloween mask manufacturer, but it is actually a front for Cochran's ancient ritual operation. The company produces masks embedded with Stonehenge fragments and microchips designed to kill children during Samhain. The 'novelties' are merely the cover for mass murder disguised as a harmless holiday promotion.

The ending leaves the outcome ambiguous. Dr. Challis successfully stops the broadcast on two stations but fails to stop it on a third. The movie ends with him screaming into the phone as the commercial airs, implying many children are affected by the deadly activation. The exact number of casualties is never revealed, creating a disturbing sense of unresolved tragedy.