Plot
Several quarry workers in Georgia discover a white cream-like substance bubbling out of the ground. Said to be addictive and sweet, the substance, marketed as "The Stuff", is sold to the general public in containers much like ice cream or yogurt. Despite nobody knowing what it is and having zero calories, The Stuff becomes a nationwide hit. One night, a young boy named Jason discovers that The Stuff appears to be alive. Despite his efforts to convince his family, they dismiss him, continuing to consume it and nothing else. Later, he is arrested by a sheriff at a supermarket after vandalizing The Stuff's displays. The Stuff continues growing in popularity, with many becoming obsessed with it.
Former FBI agent-turned-industrial saboteur David "Mo" Rutherford is hired by the leaders of the suffering ice cream industry to find out exactly what The Stuff is and eradicate it. Rutherford bands together with junk food mogul Charles W. "Chocolate Chip Charlie" Hobbs, who has lost control of his company and is now living in poverty. At the town's post office, both find the owner—a regular consumer of The Stuff—dead. They learn the item's secret: The Stuff is actually a living, parasitic extraterrestrial organism that gradually takes over the brain and mutates those who eat it into zombie-like creatures, which it then uses to make more of itself before bursting out of their bodies and leaving empty husks behind. The Stuff's weakness is that it is susceptible to fire, and Mo uses this to escape several traps set by The Stuff and zombies.
Rutherford eventually saves Jason and pairs with his lover, Nicole, an advertising executive. The trio infiltrates the distribution plant, an organized corporate effort to spread The Stuff to eliminate world hunger. Then they use explosives to destroy the lake where The Stuff is being extracted. Meanwhile, United States Army Colonel Malcolm Grommett Spears, a retired soldier, teams up with the trio and leads a militia in battling the zombies and transmitting a civil defense message for Americans to break their addiction to The Stuff by destroying it with fire. However, as they attempt to broadcast their warning, a mass of The Stuff bursts out of a zombified Charlie's throat, cornering Nicole and Jason in a recording booth. Rutherford electrocutes The Stuff, burning it, and then they make their national broadcast. The Stuff's popularity quickly plummets as the public rallies to destroy all supplies. With the crisis seemingly averted, Rutherford, Nicole, Jason, and Colonel Spears are hailed as national heroes.
Mo then visits the head of The Stuff Company, Mr. Fletcher. He tells Mo that the destruction of the mine has not hurt his business since The Stuff exists in many areas, but Mo swears to rid the world of its existence. Mr. Fletcher then introduces Mr. Evans, the ice cream mogul who had initially hired Mo, alongside with whom he now works. They introduce a new product, "The Taste", a mixture of 88% ice cream and 12% The Stuff, supposedly enough to make people crave more without it taking over their minds. An undaunted Mo brings in Jason, carrying a box full of The Stuff containers. He holds both moguls at gunpoint and forces them to consume the product as punishment for the innocent lives they have destroyed with the product. As they eat, Rutherford inquires, "Are you eating it, or is it eating you?" After they finish, Mo and Jason leave them behind as police sirens can be heard approaching.
Smugglers sell The Stuff on the black market, where one of them tastes it. In a post-credits scene, a woman in a bathroom says, "Enough is never enough", while holding a cup of The Stuff.
