Athena-1, a
space station owned by nefarious gene-manipulation company Energyne, is destroyed after a
laboratory rat mutates and wreaks havoc. Kerry Atkins, the lone surviving crew member, manages to escape in the escape pod when the station implodes, along with a trio of
pathogen canisters that Energyne
CEO Claire Wyden ordered her to retrieve, but the pod disintegrates upon re-entry, killing Atkins. One canister is swallowed by an
American crocodile in the
Everglades National Park, and another lands in a
Wyoming forest where a
wolf is exposed to the pathogen.
Primatologist Davis Okoye, a former
Special Forces soldier and member of an anti-poaching unit, works at the
San Diego Zoo Safari Park. He is friends with a rare
leucistic western lowland gorilla named George that he saved from
poachers who murdered his mother, and communicates with him via
sign language. The third Energyne canister crash-lands in George's habitat, exposing him to the pathogen. As George grows considerably larger and more aggressive, Davis is contacted by
genetic engineer Doctor Kate Caldwell, who explains that the pathogen was developed by Energyne to rewrite genes on a massive scale. She had hoped to advance research on
CRISPR as a potential cure for diseases, but discovered Energyne's plans to use it as a
biological weapon and was falsely incarcerated, during which her terminally ill brother died. George escapes from captivity and runs amok at the preserve. George calms down, but is soon captured by a government team led by Agent Harvey Russell and put on a
Boeing C-17 Globemaster III airplane. Meanwhile, Claire and her brother Brett oversee a
mercenary team's attempt to capture the mutated wolf, Ralph, which goes awry as the entire team is killed. Claire, resolving to capture Ralph and use George to cover up her plot, uses a massive transmitter atop the
Willis Tower to lure the animals – engineered to respond aggressively to a certain
radio frequency – to Chicago, unconcerned about the massive risk to civilian lives this poses. George reacts violently to the sound and crashes the plane, though Davis, Kate, and Harvey
parachute to safety. George survives the crash and joins Ralph as they make their way to
Chicago, while Davis and Kate are aided by Harvey in stealing a
UH-60 Black Hawk military helicopter in pursuit. They arrive to find George and Ralph tearing through the city as the military struggles to stop them. The crisis worsens when the mutated crocodile, Lizzie, joins the duo. Planning to steal an
antidote to turn the animals back to normal, Davis and Kate infiltrate Energyne's base of operations at the tower and take several vials of it, but are caught by the Wydens as Claire reveals that the antidote only eliminates the animals' enhanced aggressiveness rather than reversing the pathogen's effects altogether and shoots Davis, but he survives. When George climbs to the top of the tower, Claire orders Davis to distract him while she attempts to escape with Kate at gunpoint. Kate slips a vial into Claire's
handbag and pushes her toward George, who swallows her whole along with the vial, returning him to his former personality. Down below, Harvey takes incriminating evidence from Brett and allows him to escape, only for Brett to be crushed to death by falling debris upon exiting the building. As the damaged tower topples, Davis and Kate survive by crash-landing a helicopter on the
Federal Plaza. Davis stays to help George defeat the other animals, while Kate and Harvey rush to prevent the military from deploying a
GBU-43/B MOAB against them. As George battles Ralph and Lizzie, Davis tricks Ralph into attacking Lizzie, who kills him by biting off his head. Lizzie overpowers George, but Davis distracts her using grenades, a
chain gun, and missiles from a downed
AH-64 Apache helicopter. Lizzie destroys the helicopter and corners Davis, but is stabbed in the eye by George with a
rebar killing her. With the threat neutralized, the airstrike is aborted as Davis is rejoined by his allies. George initially appears to die from his wounds, but recovers and assists Davis and company in rescuing civilians. ==Cast==