In a version of Earth where giant monsters known as Titans fight often, King Kong is living in a
place called the Hollow Earth. It’s an ancient subterranean ecosystem deep within the planet
with unique gravity and constant radioactive energy that allows the creatures in it to evolve
to titanic sizes. One day Kong is being chased by giant wartdogs so he heads toward a cliff’s
edge where he’s prepared a trap for the beasts to fall into. Kong also throws a tree trunk that
activates a second trap, causing rocks to fall on his enemies. The wartdogs refuse to give up,
so Kong grabs one of them and tears it in two, roaring as the blood falls on him to prove he’s
the boss of the area. Terrified, the wartdogs run away. Afterward Kong washes himself in the
waterfall and eats the enemy he killed, growling in pain when he discovers he has a bad tooth.
Suddenly he hears a roar in the distance and the distraction allows a huge reptile to steal the
meat from him. Kong only struggles for a few seconds before letting it go, more interested
in what he just heard. He follows the noise but only finds a random little animal and not more
like him as he thought. Meanwhile on the surface, Doctor Ilene works for Monarch, an organization
who keeps an eye on the global threats posed by titans. She has a special system to watch
them all and make sure they aren’t getting in trouble. Ilene is worried about Kong because he’s
from a social species and he shouldn’t be alone. Whenever a bad monster appears to destroy a city,
the legendary Godzilla comes out of his home in the ocean to fight them and keep humanity
safe. In Rome, a giant spider-like monster starts terrorizing the streets and Godzilla immediately
appears to attack it, destroying some buildings in the process. After throwing the beast around,
Godzilla makes it explode with his atomic breath. He celebrates the victory with a roar and goes to
nap inside the Colosseum. At a Monarch outpost in Hollow Earth, the researchers detect heavy
energy readings coming from the sinkhole from Kong’s wartdog trap. Ilene is immediately alerted
about this and she flies to the Hollow Earth access point in Barbados, where Director Hampton
shows her pretty high spikes in their sensor array. Meanwhile in the Monarch Base Academy,
Ilene’s adopted daughter Jia starts feeling dizzy in class. She closes her eyes and her hands moves
on its own as snow starts falling inside the room. Suddenly she has a vision involving the Titans and
the teacher wakes her up, only to discover she unintentionally made drawings all over her school
work and the desk. After class, Jia must clean her desk and the teachers tell Ilene that Jia is
having trouble fitting in. Using sign language, Ilene tries to talk to Jia, who just says she’s
worried about Kong and that she doesn’t feel like she belongs on the surface. It turns out
Jia is the last member of the Iwi tribe from Skull Island, Kong’s original home. Later at home, Ilene
realizes that Jia’s drawings match the spikes from the sensor array. At the same time in Hollow
Earth, an unknown Titan destroys the outpost. This causes Jia to wake up from a nightmare and
Ilene has to promise there’s nothing wrong with her. The next day Ilene travels to Miami to find
conspiracy podcaster Bernie, who has helped her with Titans before. He agrees to team up with her
again as long as he gets to visit Hollow Earth. At that moment, Ilene receives an alert about
another energy surge that even Godzilla senses. He immediately leaves Rome to search for the source,
destroying more buildings in the way. At the same time, the access point opens and everyone in the
base panics, but it’s just Kong, who asks for help with his tooth. While the scientists give
Kong a sedative, veterinarian Trapper flies over in his special aircraft and uses it to pull out
Kong’s bad tooth, replacing it with a very strong metallic prosthetic. Afterwards Bernie tells Ilene
that he’s realized each spike matches a Titan appearing on the surface. His analysis concludes
this energy is a distress call from Hollow Earth. Hampton authorizes a team to go down there,
so pilot Mikael takes Ilene, Bernie, Trapper, and Jia in his very advance aircraft and they follow
Kong when he jumps back into the access point. The trip is full of crazy lights and shaking
that makes Berni feel like he’s high, but it’s quite safe and soon they make it to Hollow Earth.
A bunch of vertacines start flying near them, so Trapper explains they’re harmless and activates
the camouflage in the ship to blend in. Meanwhile a Monarch team rushes to France, where a nuclear
power plant is on fire. The soldiers find giant paw prints nearby and discover Godzilla is there
absorbing all the radiation to charge himself up. As his body starts to glow, Monarch jets fly in to
try to stop him, but Godzilla swats at them before bringing them down by expelling blue energy.
Hampton informs Ilene that Godzilla is clearly preparing for something, but the connection soon
ends because of the energy in Hollow Earth. Ilene’s team reaches the Monarch outpost and
is devastated to find all the scientists dead and the building absolutely destroyed. There’s
a bloody paw print on the stone walls that doesn’t belong to Kong, and Trapper says it’s a call for
war. They find an unbroken security camera and hope they can get answers from it. Elsewhere,
Kong gets his axe before jumping into the sinkhole he created the other day. He finds
a bunch of glowing crystals but also the bones of creatures like him. After hearing some roars in
the distance, he crosses a waterfall and discovers an uncharted subterranean realm. A shadow begins
moving toward him and he meets a young primate named Suko. Kong tries to approach him peacefully,
but Suko bites his hand and summons more apes to attack. They tackle Kong and quickly disarm him
to then use his own axe against him, but Kong is still stronger and easily pushes them away. When
Suko jumps on Kong’s face, he grabs him and uses him as a club to beat up the other apes. As they
fight, one of the apes almost falls off a cliff, but Kong grabs him and pulls him up to safety.
However the ungrateful ape tries to stab Kong with a bone dagger, so Kong kicks him off the cliff.
The final ape tries to run away in fear and Kong throws a rock at it before it leaves. Afterward
Kong roars at Suko to establish dominance and asks where the blade comes from, so Suko becomes his
guide. Eventually Suko brings Kong to a watering hole to have a drink while acting suspicious.
Suddenly a gigantic serpent monster comes out of the water and attacks Kong, trapping him with
its long body to squeeze him. Suko immediately runs away but suddenly the axe blocks his way,
it turns out Kong easily decapitated the monster. Then he takes a break to eat the serpent and even
shares it with Suko, who is surprised that he’s being fed after leading Kong to a trap.
In the aircraft, Ilene access the security footage and discovers an ape destroyed the outpost.
Suddenly an energy surge causes their ship to start going down, but thankfully Mikael regains
control just in time. Jia can sense where the surge came from, so they land the ship and follow
her directions through the jungle. Trapper starts smelling something weird and says they should turn
around, but Mikael ignores him and announces he’s in charge. At that moment a tree creature eats
him whole and the group runs away. Ilene tries calling for help but her device isn’t working.
After wandering around for a while, Jia finds some old ruins that seem to belong to the Iwi
tribe. There’s a big structure at the back with a decoration of Mothra, the queen of the monsters.
A glowing bug suddenly lies on a triangle on the wall, so Jia presses it and causes water to come
out. They follow it through the structure and find an organic protective veil. When Trapper
touches it, it starts glowing and Jia opens it to reveal the subterranean realm. In Spain, people
run in panic as a charged up Godzilla crosses the city and returns to the ocean. A Monarch
submarine tracks his trajectory and deduces he’s going to the Arctic Ocean where a very aggressive
Titan called Tiamat lives. The researchers determine that if Godzilla kills Tiamat,
he will become supercharged. A few hours later, the Monarch submarine reaches Tiamat’s domain and
notices the Titan’s energy is distorting their radar. Suddenly a light brightens the area:
it’s Godzilla’s atomic breath, which is causing some serious damage to the submarine while
destroying a layer of ice to wake up the other Titan. Tiamat quickly comes out glowing magenta
and uses its body to trap Godzilla, who retaliates by biting a chunk of its flesh. Tiamat immediately
bites back and Godzilla starts to charge up by absorbing its energy, causing an atomic beam that
even reaches the surface. The mighty Tiamat becomes sushi and Godzilla enters its lair,
where it rests as it absorbs all the energy in the area. Back to Ilene’s team, they hear a noise and
suddenly get surrounded by warriors with spears. However they also recognize Jia and decide to take
the group with them. They reach a glowing cave and realize this is an entire Iwi civilization,
who communicate with each other through telepathy. On the ceiling they notice various vortex portals,
which could potentially take them all over Earth. The leader of the tribe touches Jia’s hands and
they both share memories: the leader shows Jia the life of the tribe and in return Jia shows her life
on the surface. The leader is pleased and orders her guards to let the rest of the team go. The
group is taken to a crystal formation and Ilene realizes that the distress signal came from here.
They sent it with the big crystal to warn Godzilla about an incoming danger. Further into the Iwi’s
temple, some special water is poured to light up the place, revealing the Iwi history on the walls
which Ilene translates. Long ago, the Great Apes were humanity’s protectors, but a ruthless leader
known as the Skar King led an army of apes to try and attack the surface world in a war against
Godzilla and his species. Godzilla stepped in and trapped the Skar King and his army in Hollow Earth
to prevent them from attacking again. However this danger will come back and Godzilla is now charging
for it. Only a direct descendant of the Iwi will be able to reawaken Queen Mothra to bring back
peace. Meanwhile Kong follows Suko on a bridge made of bones and enters a very hot area where
he’s shocked to discover other Great Apes being held as slaves and forced into hard labor. When
a guard punishes a worker, Kong comes to help and earns the guard’s fury. Kong just punches the ape
down and demands to see the monster in charge. At that moment the Skar King comes out and sees
King’s metal tooth, so all the apes laugh at him. Then Skar King tries to punish Suko for bringing
Kong, only for the worker from before to defend him. The Skar King kicks the ape into a pit of
lava and Kong roars to complain. A fight ensues with Kong using his axe while Skar King uses a
whip made from another Titan’s spine. This weapon almost chokes Kong to death, but he manages to
grab Skar King and throw him off. Refusing to lose, Skar King uses a glowing crystal at the
end of his whip and reveals Shimo, the Titant that caused the Ice Age. The whip crystal causes Shimo
lots of pain, so it’s forced to obey Skar King. It breathes an ice beam toward Kong, who tries to
deflect it with his axe. However but the blast is too powerful and it envelopes Kong’s arm in ice,
causing it to get frostbite. Kong is too weak to fight, so Suko calls him to lead him out of the
cave. Dodging another ice beam, Kong manages to run away while the other apes steal his axe. They
soon start chasing after Kong, who runs fast and releases trap after trap to bring down a bunch of
enemies. Eventually he’s cornered against a rock wall and the apes dodge another trap trigger,
only for the rocks to fall anyway and crush them. It turns out Suko activated the trap. Kong is
still in pain, so Suko helps him move and together they make their way to see the humans, unaware
that an ape survived and is following them. In the meantime, Jia connects with other Iwi teens and
finally feels like she belongs. Bernie records everything he sees, amazed by the Iwi’s use of
crystals to build their civilization. Suddenly a horn alarm wails and the Iwi rush to open the
veil, finding Kong with his wounded arm. This is seen by the enemy ape, who immediately leaves to
report to its boss. Skar King gathers an army and leads them while riding Shimo, ready to start an
invasion while Suko sees them from afar. In the Arctic, Godzilla awakens and breaks the ice,
showing its new magenta glow. Back to Kong, he’s too weak and falls to the ground, so Jia tries to
tell him they’ll take care of him. Trapper scans the injury and announces he’s been working on a
device called “Operation Powerhouse”, which he designed to give Kong a boost in case another
powerful Titan appeared. He goes back to the destroyed outpost to bring a bunch of pieces and
reveals a giant glove that he puts around Kong’s injured arm. It takes Kong a moment to get used to
it but soon he regains mobility and punches the ground, pleased with the result. At that moment
Suko comes to warn them about Skar King’s plans, so Kong immediately jumps through a vortex portal
to appear in the middle of Egypt, damaging the pyramids and causing people to fall. In Gibraltar,
Godzilla hears Kong’s roar and jumps into the sea to go find him. At the same time in Hollow Earth,
the Iwi get Jia ready and the girl approaches a large crystal, using her hand to activate some
gold energy. This wakes up Mothra, who thanks Jia before flying to the surface. Then the Iwi start
evacuating the cave. After destroying bridges with his swimming, Godzilla reaches Egypt,
where Kong tries to explain the situation. However Godzilla thinks Kong wants to attack humanity and
pushes him against the pyramids. A fight ensues and Kong manages to land some good punches thanks
to his mechanic arm. Then he grabs Godzilla’s tail and stars dragging him toward the portal,
only for Godzilla to glow and shoot his atomic breath, destroying more pyramids. He pushes
Kong down and charges again, but this time Mothra appears and pushes him back. Jia also appears and
together with Mothra they use telepathy to finally explain the situation. Godzilla roars to agree to
team up. Ilene’s team follow the Iwi to the area underneath the pyramids, where they pour a red
liquid into the water that causes the crystals to move. Hopefully this will create a gravity
surge that will hold the evil Titans back. At that moment Skar King breaks the veil and comes inside,
making Shimo freeze the crystals before they can finish the process. Trapper gets on his aircraft
and brings over a bunch of vertacines, who attack the ape army with bio-electricity. While the group
escapes in Trapper’s ship, Shimo shoots ice again to scare the vertacines away. Thankfully Godzilla
and Kong show up and jump to meet with Skar King and Shimo at the same time the crystals release
the surge. The gravity causes the Titans to float around, but that doesn’t stop them from attacking
each other whenever they have the chance. Trapper’s ship almost gets smacked too, but Mothra
comes in to protect them and the portals. Some ape soldiers try to join the fight so Suko jumps
in too, throwing rocks at them to keep them away. Shimo shoots ice at Godzilla and almost freezes
him, however Mothra distracts it and Godzilla breaks the ice with its magenta charge. Then
Mothra catches Trapper’s ship and puts it down while Suko kicks an ape guard off to its death.
Kong recovers his axe from the enemy and exchanges blows with Skar King and his whip, but sadly Kong
loses his axe again when a portal opens and drags all the Titans to Brazil. The people on the beach
immediately run away in panic as the waves freeze and the Titans break through the ice. Skar King
makes Shimo unleash its ice powers, causing the sky to go black before it starts freezing the
city too. Suddenly Godzilla shoots an atomic beam at Shimo at the same time that Kong punches Skar
King, causing him to lose a tooth. The fight continues among the four Titans as they throw
each other all over the place, destroying dozens of buildings. After Skar King tosses a building
with his whip, he and Shimo attack Kong together, forcing him to use the glove to protect himself
from an incoming ice beam. At that moment Godzilla finishes charging and shoots at Skar King, who
dodges the attack and retaliates with his whip. Godzilla catches it with his mouth and uses it to
throw Skar King down before breaking it, causing the crystal to fall. While Kong continues to be
under Shimo’s beam, Godzilla shoots at Skar King again, who jumps to dodge and recover the crystal,
only for Godzilla to shoot it out of his hand. Then Godzilla jumps on Shimo to attack it while
Kong and Skar King begin fighting to get to the crystal. Suddenly Suko appears with the axe and
shatters the crystal, which sends a shockwave that throws all the Titans back. Shimo quickly recovers
and realizes it isn’t under Skar King’s control anymore. When Kong and Godzilla start throwing
Skar King around like a tennis ball, Shimo shoots his ice beam and freezes its slaver as revenge.
Now Kong can throw him on the ground to shatter him to death while Godzilla uses his breath to
clean up the sky. With the fight finally over, Mothra takes Jia back to the Hollow Earth and
the girl confirms she wants to keep living on the surface with Ilene. Mothra repairs the veil,
and a tired Godzilla returns to rest at the Colosseum. Kong and Suko ride Shimo back to
the ape tribe, where Kong earns the gratitude of the slaves and becomes their new leader.