In 1979, Skylab is decommissioned and reenters Earth’s atmosphere, but a fragment of an oxygen tank survives and lands in Western Australia, where a farmer creates a makeshift Skylab museum around it and preserves what remains of the mission.
In 2007, biochemist Dr. Hero Martins, accompanied by Pentagon bioterror operatives Liam Neeson as Robert Quinn and Lesley Manville as Trini Romano, travels to a tank that carried an infectious fungus for study. Tragedy strikes when a heavily mutated fungus escapes during an attempted clean, killing the farmer and many nearby people. Martins collects a sample, but a boot-scorched patch she steps on corrodes her hazmat suit and gradually begins to control her actions. In a moment of clarity, Martins takes her own life. The military incinerates the farm and the affected bodies, while the fungus sample is stored in an underground cold storage vault at the Atchison Storage Facility in Kansas.
Over the years, the government seals the vault and leases the ground level to a self-storage company. In the present day, elderly Ma Rooney enters a storage unit with the intention of ending her life, while night guards Travis Joe Keery and Naomi Williams Georgina Campbell begin hearing a beeping alarm that signals a malfunction in the vault’s systems caused by rising temperatures. A military officer who calls herself “Abigail” (Ellora Torchia) contacts Robert, warning of the fungus’s dangers. Recognizing the escalating threat, Robert agrees to return to Kansas, and Trini drives him to pick up a device at her home.
As Travis and Naomi approach the sealed vault, they confront an ever more aggressive outbreak: an infected rat king stands outside the door, while fungus claws its way out of the storage, infecting whatever it touches. An infected cockroach hitchhikes into a car with Naomi’s ex-boyfriend Mike [Aaron Heffernan], whose dead cat is revived and immediately self-destructs in a shocking display that spreads the fungus further. Mike and a deer become infected, and the deer inflates and explodes, accelerating the spread. The two guards seek safety in a storage unit, contacting the military for help, and Abigail guides them toward Robert, who urges them to stay hidden.
Griffin [Gavin Spokes], the storage facility manager, arrives with a biker gang to steal televisions, further complicating the crisis. Mike infiltrates the gang and infects many as chaos erupts. In a turn of events, Ma Rooney intervenes and saves the day, allowing Robert to reunite with Travis and Naomi. Robert delivers a backpack nuke to be placed outside the vault door to annihilate the entire facility and stamp out the fungus. The trio places the device, killing one infected creature along the way, while Griffin is killed by Trini as she confronts him. Robert then falls during the pursuit, unable to rise, and the group escapes in Trini’s car just as the bomb detonates, destroying the source of the outbreak.
In the days that follow, Travis spends time with Naomi and her daughter, while Robert recovers in the hospital, with news coverage praising his actions to avert a broader disaster, though criticizing the military’s earlier missteps. A visitor named Ishani—Abigail’s true name—reveals she leaked Robert’s reports about the fungus to the press, adding a layer of political reckoning to the cratered tale of containment and sacrifice.
