In 1993, scientists found a new technology known as CRISPR which allowed them to treat incurable
diseases through genetic editing. However in 2016, the US government banned CRISPR
because of its potential for misuse, calling it a weapon of mass destruction. In the present day,
the space station Athena-1 is in absolute ruins and the entire crew is dead except for Kerry,
who is asking the control room for help. However her boss won't open the door to the escape capsule
unless Kerry retrieves the mutagen samples first. Afraid but desperate to survive, Kerry goes
through the wreck and secures the three samples, but unfortunately she's spotted by the enemy.
It turns out that an experiment gone wrong has created a monstrous mutated rat that went crazy,
and now it's coming after Kerry. The astronaut rushes away, dodging the debris and the flames
as fast as she can, and she makes it into the escape capsule right before the rat can catch her.
Kerry leaves and watches the station explode, but unfortunately the rat's rampage has damaged the
capsule too, so it also explodes and kills Kerry while the pieces fall to Earth. Sometime later at
San Diego Wildlife Sanctuary, primatologist Davis introduces his friend Nelson and two new employees
to the gorilla enclosure. The newest member Paavo is quite aggressive and is bothering the females,
so Davis uses sign language to calm him down. At that moment, Davis' best friend George shows up,
and the presence of another male gorilla causes Paavo to get aggressive again. One of the
employees gets scared and tries to run away, so Paavo goes after him and pushes him to the floor.
But before anything serious happens, George cuts in and scares Paavo away. Once it's over,
George and Davis exchange many jokes through sign language, and Davis reminds George that
Paavo is family now so he also must be protected. When Davis asks for a fist bump, George gives him
the middle finger first. Afterward, one of the employees tries to ask Davis out, but he turns
her down, and Nelson teases him for preferring animals over people. Later in the evening,
the three mutagen canisters that Kerry retrieved arrive on Earth. One lands in the sanctuary
and sprays George with its contents. The second one lands in the forest and is found by a wolf,
while the third one falls into the river and it's swallowed by a crocodile. The next day, Davis
arrives at the sanctuary to hear bad news from Nelson: George's behaving unusually aggressively
and has broken into the grizzly enclosure, where he killed a bear. When Davis checks on George,
he discovers the gorilla has been wounded by the bear too. George is sad, and he admits he made a
mistake and apologizes, but the biggest shock is that George has grown much bigger in size. Davis'
team investigates the area and when they find the canister, Davis decides to keep it for research.
Later, he studies George's bloodwork and thinks it doesn't make any sense because there's a lethal
concentration of growth hormone, which should've killed him instantly. Nelson thinks George should
be put down, but Davis refuses until they learn more. Meanwhile siblings Brett and Claire are
having an argument. Their company Energyne is the one behind the research of the mutagen, and Brett
is furious over all the money they've lost when the station exploded. However Claire is happy with
the results because the mutated rat confirms the Project Rampage experiment is successful. She also
has hope for progress because there's a report from the Meteor Society revealing the location of
one of the containers, which was made to withstand reentry, so she hires Burke and his private
military service to fetch it. Burke's team travels to the forest and discovers that the canister has
been damaged and emptied, plus all the wolves have been killed, which they report to Claire. This
makes her realize the wolf is mutating, so she orders Burke to capture the beast. In the city,
Kate watches the news and learns both about the Athen-1 tragedy and George's attack on the bear.
Because she's a former Energyne scientist, she puts two and two together and rushes to
the sanctuary, where she tells Davis that the canister he found is a sample she made. Davis
is wary of her, but Kate begins mentioning all the symptoms George's going through to prove she's the
real deal and the only one that can cure George. It turns out the mutagen is editing George's DNA
by mixing with DNA from other animals, causing him to grow rapidly and become more aggressive.
Suddenly George becomes enraged and starts hitting the cage until he breaks it and escapes.
Then he begins storming through the sanctuary and spreading chaos among the guests, even destroying
cars with his fists. The police immediately arrive and get ready to shoot him, but Davis cuts in and
calms George down using sign language. The cops put down their guns, but a sniper in a helicopter
doesn't get the memo and knocks George down with tranquilizer darts. Meanwhile in the forest, Burke
and his team come across Ralph, the mutated wolf. They manage to shoot him down from the helicopter,
then they land to go looking for the body. However the body is gone and instead they find a huge paw
print on the ground, which makes a few soldiers scared. Moments later, Ralph suddenly attacks
and begins killing all the soldiers one by one. They try to defend themselves with their weapons,
and the helicopter uses a machine gun as well, but after the earlier shot, Ralph has developed
a very thick skin and the bullets only tickle him. He's also grown so big that he can leap incredibly
high in the air and attack the helicopter, destroying it. On the ground, Burke is the only
survivor and attempts to fight the wolf again, but Ralph easily devours him. In the evening,
Davis and Kate are arrested by Agent Russell of the FBI for doing illegal experiments on George,
who is being taken away in a government plane with them. When Davis sees George in the cage,
he notices his wounds are already healing. Then Russell tries to interrogate them, teasing Davis
for quitting the army to take care of animals and behaving like a complete twat by insulting the
duo and ignoring their warnings on how dangerous it's to keep George in a plane. He also reveals
that Kate was fired from Energyne two years ago after she tried to steal the company's research,
for which she spent thirteen months in prison. This causes Kate to admit she can't actually cure
George, and now Davis doesn't trust her anymore. Back in Energyne, Claire learns Kate was arrested
and Brett thinks she's gathering evidence to bring down the company, so he sees her as a threat. It's
also revealed that Claire does have a cure for the mutagen, so she makes a plan: she'll attract
all the mutated animals to her building by using low-frequency radio waves and the military will
be waiting for them to kill them, that way Claire can collect the DNA and sell it later. She doesn't
worry about Kate because she's sure George will kill everyone in the plane sooner or later. When
Claire turns on the device, Ralph immediately stops rampaging through the roads and the cars
and starts making his way to the city. Lizzie the mutated crocodile also senses it and takes
off as well. On the plane, George is supposed to be sedated, but Claire's trick makes him wake up
absolutely furious. He destroys the cage and starts wrecking everything that surrounds him,
tossing people around as if they weighed nothing. The guards start shooting at him to no avail, and
when Russell tries to go after him, George quickly knocks him down under his foot. Davis tries
talking to him, but at that moment another soldier starts shooting again, enraging George once more.
A bullet ends up hitting a box of explosives that blow up and destroy the plane's turbine,
causing it to start going down. While George is pushed against the wall by a cart, Davis rushes to
put parachutes on himself, Kate, and Russell, and they manage to jump off the plane right before it
crashes with George inside it. However when they land and check the crash site, they don't find
the body. There's a trail on the grass though, indicating George survived and is making his way
to the city too. At Energyne, Claire's furious to hear Kate survived the plane crash when the FBI
arrives to take away all of the company's research and records. Attempting to clean her own name,
Claire tells the agents that it was Kate behind all the chaos caused by the beasts. Back to Davis,
he tries to leave Kate behind because he's tired of always seeing the worst of humanity,
which he's already got a lot of during the war. When he rescued George, he was just a baby hiding
under the car while he watched people butchering his mother. However Davis decides to give Kate a
chance when she explains why she created CRISPR: she wanted to cure her brother's deadly illness,
but when the company wanted to weaponize the mutagen, she tried to destroy it and was sent
to prison for it. While she was locked up, her brother died. Russell also now likes the duo
because they saved his life, so he gets in contact with his men to be rescued. The group is then
taken to an air force base, where Colonel Blake shows them footage of George and Ralph running
to the city. Davis points out is impossible for a gorilla and a wolf to travel in a straight line
to the same destination, and Kate says they're being called by something, meaning Claire must
be waiting with an antidote. Russell defends their advice, but Blake doesn't want civilians involved
and sends them away. Outside, Davis tries to negotiate with the soldiers to let them go,
but since it doesn't work, he starts a fight and quickly knocks both guards out. Then they
try to steal a helicopter, and when Russell sees them, he gives them the keys and a phone to stay
in contact. Meanwhile Blake's team attempts to stop the beasts, but their weapons including
the big explosions are useless, and the entire army is wiped out. This makes Blake decide to
evacuate the city before the beasts get there, and Russell sends that information to Davis,
who doesn't think they can get everyone out in time. When George and Ralph arrive at the city,
the destruction immediately begins: they bring down buildings, destroy vehicles, and even hit any
helicopter that comes closer. The military meets them with a vast army of tanks and weaponry, but
nothing works, and the beasts just keep themselves busy wrecking everything in their path. Soon
Lizzie also arrives through the river, joining the other beasts to cause even more damage,
using its big mouth to bite the tanks and jets that get in the way. Desperate for a solution,
Blake orders his men to get a bomb ready to wipe out half of the city. Russell tries to
change his mind, explaining Davis and Kate are on their way to retrieve the antidote,
but Blake doesn't trust them after they stole his helicopter and kicks Russell out. At that moment
Russell gets the result of the evidence found in the company and calls for a ride so he can
do some arrests. While the jet with the bomb takes off, Davis and Kate make it to Energyne and steal
three vials of antidote. However Claire sees them on the security cameras and comes to stop them,
explaining the antidote stops the aggression but will keep the beasts' size. Then she takes the
vials from Kate and shoots Davis, who falls to the ground unconscious. Afterward Claire takes
Kate as a hostage and takes her to the roof with her, but before they can escape in a helicopter,
George climbs to the top of the building and breaks the helicopter's tail. This also almost
kills Kate, but at that moment Davis comes back and grabs her as he explains the bullet didn't
hit any vital organs. While George proceeds to destroy the antenna sending the signal,
Kate reveals that she managed to keep one of the vials, so they can still save George at least.
Claire tries to confront the duo again, so Kate uses the chance to put the antidote in her bag
before punching her as Davis calls for his friend. George comes forward and grabs Kate to eat her,
therefore getting the antidote as well. Meanwhile Brett is trying to escape through the stairs,
taking the last computer and a lab rat with him so he can make business again later. He
bumps into Russell on the ground floor, and the agent takes the things from him in exchange for
letting him go instead of arresting him. However when Brett makes it outside, he's suddenly crushed
by falling debris. Outside, Lizzie and Ralph join in the destruction of the building while George
starts to calm down thanks to the antidote. Davis and Kate take the broken helicopter right before
the building crumbles down, causing the helicopter to crash to the ground but also allowing the duo
to survive. Then Davis notices there are lots of civilians still around, and that George is
finally feeling better. Lizzie and Ralph are fighting each other, so Davis tells Kate to go
find Russell while he arms himself up and joins the fight with George. The beasts roll around and
exchange vicious hits, but in the end it's Lizzie who kills Ralph by biting him on the neck. Now
it's George versus Lizzie, but it seems George is struggling to gain the upper hand, so Davis throws
a belt of grenades at Lizzie's back. Unfortunately Lizzie has grown very powerful and the grenades
don't do much damage. Lizzie recovers quickly and throws George against a building, causing
a steel bar to go through the gorilla's chest. Then Lizzie tries to come closer to finish him,
but Davis comes through and uses as many weapons as he can take from the helicopter to distract the
crocodile. Lizzie falls for it and begins going after Davis, almost killing him. However George
takes the steel bar and jumps in the air to stab Lizzie in the eyes, finally ending the fight. Kate
reaches Russell and tells him about the antidote, who calls Blake to pass the message. Blake notices
the deaths on the screens and decides to abort the airstrike mission, accepting George is on
the good side. Unfortunately George passes out after winning, and Davis has to take a moment
to grieve his best friend. But when he's about to leave, Davis notices some twitching and realizes
George is just messing with him. The gorilla offers his middle finger before Davis and he
share a fistbump. Now Davis' next mission is to find a place where they can place George.