In the quiet town of Arborville, California, a meteorite crashes near the community, setting off a chain of unnerving events. An elderly vagabond stumbles upon a glistening sphere inside the meteor’s impact zone, and from it emerges a vast, slime‑like substance that clings to his hand. Three high school friends—Paul Taylor, a star on the football team; Meg Penny, the school’s bright cheerleader; and Brian Flagg, the outsider—bring the distressed man to a hospital, hoping for help. But the moment Brian departs, Paul witnesses a horrifying transformation: the lower half of the rescued man dissolves away as the Blob tightens its grip. When Paul cries out for aid, the Blob descends on him, and Meg returns to find Paul being consumed, the grotesque entity seeping out of the hospital as it grows.
As Brian and Meg struggle with unsympathetic police intervention, they retreat to a diner to regroup. Meg breaks down the terrifying truth to Brian: the Blob is on the loose. The diner’s handyman, George, becomes a grim precursor to the terror when he is fatally dragged into the sink’s drain. The Blob stalks the diner's premises, slipping into the walk‑in freezer before retreating, then moves on to claim the diner’s owner and, soon after, Sheriff Herb Geller, reentering the sewers to continue its rampage. Meg and Brian dash back to the police station, where they learn that a military operation is underway under the direction of Dr. Meddows. The scientist orders a quarantine for the town and the two teenagers, while Brian slips away and Meg learns that her younger brother Kevin has sneaked into the local movie theater with his friend Eddie.
In the theater, chaos erupts as the Blob drags its victims into a silent, hungry maw, killing several staff members and audience members. Meg volunteers to rescue Eddie and Kevin as panicked patrons scramble for the exits. Backstory emerges: the Blob is revealed to be a Cold War‑era biological warfare specimen that scientists launched into space, hoping it would be contained by the void. Instead, it fed on bacteria altered by space radiation and ultimately crashed back to Earth, swelling into the deadly, predatory mass that now stalks Arborville. Brian evades capture by commandeering a motorcycle and slipping into the sewer labyrinth, while Meg and Kevin flee the carnage. Eddie becomes another casualty of the Blob’s appetite, and Kevin barely escapes by climbing a pipe to safety.
The pursuit intensifies as government agents search the sewers, about which Dr. Meddows insists on tighter control. Meg and Brian reunite, and Meddows orders a full quarantine of the sewers, but Brian counterattacks with a surviving agent’s grenade launcher, blasting open a manhole to confront the scientist publicly. Public opinion begins to swing against Meddows as he brands Brian as infected and dangerous, even attempting to execute him. In a deadly twist, the Blob drags Meddows into the sewers, becoming a symbol of unchecked power and misused science. Explosives and grenades briefly inflame the creature, but they only inflame its hunger, sending it surging from the sewers to terrorize the town once more. Reverend Meeker, burned and driven mad by the chaos, proclaims the event the end of the world, though his sermon is interrupted by the Blob’s relentless advance.
Meg intervenes, grabbing a fire extinguisher and striking the Beast with its cooling gas, a move that unsettles the creature enough to reveal a surprising weakness: cold slows and stuns it. A plan forms in the community’s last stand at the town hall. The survivors barricade themselves with furniture and extinguishers, but the Blob overruns half the building and claims Deputy Briggs, a casualty that underscores the gravity of the threat. Brian rushes to the town’s garage and finds a snowmaking truck equipped with liquid nitrogen canisters. He scorches forward, spraying the Blob with a cold spray that provokes its rage and causes it to knock the truck over, trapping him. Desperate, Meg lures the Blob away toward a set of canisters rigged with an explosive charge taken from a dying soldier.
As the creature closes in on Meg and Brian, the blast erupts, and the ensuing liquid nitrogen envelops the Blob, freezing it in a crystalline prison. The cold snap seals the mass in place, and Moss Woodley, a survivor played by Beau Billingslea, stores the Blob’s icy remains in the town’s icehouse, a quiet memorial to the town’s near‑apocalypse.
In the aftermath, a field‑tent church service becomes the stage for a final, unsettling moment. Reverend Meeker, now scarred by burns and unravelling morally, preaches a doomsday sermon. When asked when the reckoning will come, he simply answers, “Soon.” He then withdraws a small glass jar containing a still-living fragment of the Blob, whispering, “The Lord will give me a sign.” The scene closes on this chilling hint that the town may still be haunted by what it has seen, and by what it could still become.
