In the quiet coastal town of Longhead Bay, a sinister threat begins to creep through the streets: crawling alien forehead parasites that slip into bodies and take control from within. At the center of the story is the enigmatic Dr. Sheila Baxter, who becomes convinced that true independent thought lives not in the brain but on the forehead, and she launches experiments on her colleague Dr. Philip Latham, an affair that complicates loyalties and rumors alike.
Two sailors, Big Dan Frater and Dutch "The Swede" Annacrombie, arrive in town and quickly strike up a wary friendship with the local librarian, Millie Healey. They begin to sense something deeply unusual about the townsfolk, who grow increasingly unusual and distant as foreheads begin to claim control. After they encounter a crawling forehead and manage to crush it, they report the incident to the police, only to be met with disbelief and indifference, a pattern that will repeat with dire consequences. Chief Bartnett is drawn into the confusion and suspicion, only to be overtaken by one of the alien intruders himself.
As the plot thickens, Dr. Sheila Baxter makes a darker move: she strikes a deal with local hoodlum Nick Vassidine to obtain more foreheads for her experiment. Nick’s moll, the sultry but dangerous Droxy Chappelle, seduces the inebriated Big Dan and leads him to open the freezer aboard his boat where medical cadavers are stored, allowing the aliens to harvest even more foreheads. The situation spirals as Dr. Applethorpe — already under alien influence — mistakes Philip for a fellow mindreader and invites him to a secret gathering where the aliens debate disguises; they eventually settle on peculiar headpieces with veils to blend in.
The trio of Millie, Big Dan, and Dutch search the town’s library for a reference on how to combat these parasitic foreheads. A forehead attaches itself to Millie, who is briefly captured before they manage to free her and subdue the offending creature. The attached forehead confesses its origin: their race came from a war-ravaged planet—“similar to your Earth, except different”—and their mission is to inhabit human bodies as hosts. The group brings the forehead to the police only to find that the Chief is already one of the invaders, forcing a heart-stopping chase through the town.
Meanwhile, Philip’s indiscretions come home to roost as he confesses to his wife, Mary Latham, yet he continues with the experiments, and the creeping forehead grows into a horrific monster with a giant, bulbous presence that transforms him and sends him fleeing in terror. The situation worsens as Dr. Sheila Baxter, Nick Vassidine, and Droxy Chappelle all fall under alien control. Millie discovers a crucial clue in a book: certain sound frequencies can harm or repel foreheads. Armed with this knowledge, she and the sailors craft a plan using bells to deter the invaders—an approach that buys them time, but only briefly.
The aliens return with new countermeasures—earplugs that dull the effect of sound—and capture Millie and her companions. Into this chaos steps Philip, who returns in a damaged, fearsome state. In a final act of sacrifice, he detonates the fire alarm, knocking out the possessed but also destroying himself in the process. The town reels from the assault as the remaining human resistance clings to the hope that the threat has been stopped.
The film closes with a bleak after-credits beat: a final forehead crawls into a prop rocket, muttering of revenge and vowing to return. The town’s fragile sense of safety is unsettled, leaving open the possibility that the encounter with these cosmic invaders might not be over.
> Note: Throughout the tale, the ensemble cast threads through a web of secrecy, temptation, and danger, with each key character briefly stepping into the spotlight before the horror tightens its grip.
