In the year 1928, a mountaineer is camping in the Karakoram Mountains in India. Suddenly a
mysterious glowing thing appears outside his camp and he decides to take a closer look,
only to discover a giant light ball covered by a thin layer of ice. After staring in awe
for a moment, the man tries to hit it with his pickaxe, which immediately makes him fall and
faint as the sphere glows brighter. When he wakes up moments later, he discovers the sphere is gone
and there’s a weird-looking scar on his body. Years pass and it’s now 2008. An astrobiologist
named Helen teaches at Princeton University before going home to her stepson Jacob. The boy has been
distant since his father died, but Helen still cares for him deeply. Suddenly Helen gets a phone
call from an unknown person, who tells her that a car is coming for her. At that moment, the police
surround the house and an FBI agent knocks on the door to tell Helen she must come with them now. He
refuses to explain anything and Helen doesn’t want to leave Jacob alone, but fortunately the neighbor
comes to see what’s going on and Helen can leave Jacob with her. Afterward, Helen is taken away
in a car, but the FBI agents still refuse to answer her questions. Eventually they arrive at
an airfield, where Helen boards a helicopter full of scientists from different fields,
like a nuclear physicist and a civil engineer. Just like Helen, all these scientists were taken
from their homes without an explanation. Moments later, the group arrives at the Lynwood Military
Academy in New Jersey, and the military asks everyone to leave their cell phones at the
entrance. Helen acts quickly and hides her phone under her clothes before she’s taken
away by her old friend Michael, who put Helen on the vital list because of her work with a famous
doctor called Karl. Then Michael gathers all the scientists in a room to do a presentation on the
current situation. It turns out an unidentified object from space is approaching Earth following
an unconventional trajectory, and according to their preliminary calculations, the object will
inevitably collide with the planet. Because of its huge speed, it is impossible to shoot it down,
so the government has decided to form an emergency response team that must deal with the consequences
of this catastrophe. The team only has a little over an hour before the cosmic object crashes
on Manhattan and kills around eight million residents. After the meeting, Helen locks
herself in the bathroom to call Jacob and tell him to hide in the basement, although she doesn’t give
him the details. Her conversation is overheard by one of the soldiers, but instead of arresting her,
she asks to borrow the phone because she wants to call her family too. Afterward, the scientists
travel to the site where the object will impact and quickly get alarmed because the object can’t
be identified and the rocket launch system is blocked. Terrified, they hold hands and count down
the last few seconds, but to their shock, nothing happens. At that moment, they see through the
window a bright ball of light slowly approaching Earth until it lands in the middle of Central
Park, causing people to run away in terror. The scientists immediately put on protective suits and
carefully approach the glowing sphere, feeling like there’s something in the air around them,
perhaps electromagnetic waves. Soon the police and the military show up with weapons and surround the
area, and at that moment, a light begins glowing brightly on the sphere as an alien creature
emerges to meet them. Helen slowly approaches the alien and he extends his hand to her, but when she
tries to reach back, a shot is fired and the alien falls into her arms, visibly bleeding. Suddenly a
huge creature appears out of the light and uses its powers to take away electricity in the area
and incapacitate every piece of machinery, it also emits a terrible ultrasonic sound that
stuns everyone’s ears. Then the creature reaches for the wounded alien, but the alien stops it with
a mere gesture and the robot immediately shuts down, allowing machinery to go back to normal.
Afterward the injured alien is taken to a military laboratory, but the medics don’t know how to
treat an unknown creature, and they lose so much time that the alien begins getting worse. Helen
advises them to bring in a surgeon to at least remove the bullet and they do exactly that. The
surgeon makes an incision and removes the bullet easily, but he’s also surprised at how similar
to humans the alien is inside. He also notices that the gray skin-like tissue is cracking and
separating from the alien's body, so he proceeds to remove the entire layer. To everyone’s shock,
the remaining creature looks very human. Next, the alien is put in a special protective capsule where
his condition is monitored. Helen notices he’s dreaming, and at that moment the alien wakes up,
immediately panicking when he sees the capsule. With a friendly voice,
Helen talks to him and tells him there’s no danger, and the alien calms down while it’s
revealed he looks exactly like the mountaineer from 1928. For now he doesn’t answer questions,
he only repeats Helen’s words. Meanwhile humanity is going through chaos and panic. Stock exchanges
are closing, and New York citizens are being prepared for urgent evacuation. People around
the world are also fleeing population centers on their own, fearing an alien invasion. While the
president and vice president hide in a shelter, the Secretary of Defense Regina holds an emergency
meeting and learns that the aliens have managed to hack into one of the spy satellites, so now
they have all the classified information about national defenses. To make matters worse, more
of these glowing spheres are landing all around the world. Arriving at the lab, Regina listens to
the scientists' report: flesh samples taken from the alien show the presence of DNA from three
different life forms. The creature's body tissues are human, and the gray flesh shell is organic,
which is a kind of protective suit of placenta. It seems the aliens had previously visited Earth
and obtained a sample of human DNA, explaining the mountaineer’s scar and why the alien could
take a human form. Afterward, the group visits the alien, who is speaking perfect English and
asks for water. His hand trembles as he brings the glass to his mouth, and he explains that it will
take time for him to get used to this body. Regina tries to interrogate the alien, but her questions
are ignored. Then Helen asks him to tell her about himself, so the alien introduces himself as Klaatu
and says that he is a representative of a group of civilizations. He asks for a special meeting with
the UN so he can talk to all the world leaders, but Regina refuses. Seeing as Klaatu won’t offer
any more details, Regina orders for him to be injected with truth serum and sent to a safer
location for interrogation. The scientists believe that Klaatu is the most important
discovery in human history and don’t want to hand him over to the secret service, but Regina thinks
this alien is a great danger to humanity and that falls under the jurisdiction of the Secretary of
Defense. Michael and Regina get into an argument only to be interrupted by Helen, who assures them
that she will personally inject the alien and perform all the necessary tests. Then Helen is
given a vial of truth serum, but she sneaks into the pharmacy and secretly takes a vial of regular
saline too. Meanwhile Regina tells Klaatu that he’ll be transferred to a more secure location,
and when Klaatu says he intends to leave, Regina informs him she won’t let him because he has
illegally invaded this planet and his huge robot has attacked the military. Klaatu points out that
the biorobot is only activated in the presence of violence, but Regina ignores that detail and
orders Helen to administer the injection. Helen gives him the saline instead of the serum as she
whispers to him that he must run. Afterward, Helen is immediately taken away and Klaatu is
tied to a chair before he’s taken to a room with a lie detector, where an agent asks him a series
of control questions and monitors his readings on a monitor. Klaatu only offers a few vague answers
before he uses his power to reprogram the lie detector and electrocute the agent. Then Klaatu
takes control of the man's mind and asks him how to get out of the military base, he also orders
him to give him the suit. Next, Klaatu uses his powers to take control of the security cameras and
learns the location of all the guards so he can stun them all with ultrasound. An alarm goes off,
but as everyone panics and runs around, Klaatu leaves the building quietly. In the middle of
the chaos, Helen steals a sample of the alien's flesh, and Regina orders the use of all available
resources to capture the fugitive. Eventually Klaatu arrives at the train station, where there
is also complete chaos because of all the canceled departures. Because his body is part human,
Klaatu feels hunger, so he uses his powers to get a free sandwich from a vending machine while
a kid watches in awe. Klaatu uses this chance to watch how society behaves, noticing how aggressive
everyone is getting over having to wait. Suddenly he becomes ill and rushes to the bathroom, where
he notices that he's bleeding and promptly passes out. Seconds later, Helen gets a call at her house
telling her a patient is asking for her at the station. Realizing that it must be the alien,
Helen immediately drives to the station and picks him up. Then she takes Klaatu to her car,
where he meets Jacob, who is behaving rather rudely. Klaatu asks Helen to give him a sample of
the gray tissue that was removed from him, and he uses it to dab it on his wound, instantly healing
it. Meanwhile the American military attempts to attack the biorobot, which detects the approaching
danger and immediately activates. Thanks to its powers, it’s easy for it to gain control of all
military equipment and destroys it in seconds. All attempts to attack the alien fail, leaving the
military leaders without knowing what to do. Back to Helen, she drives down a specific route that
Klaatu asks her to follow. Jacob notices all the cars trying to leave the city and expresses his
hate for aliens, saying they should be destroyed and that his father would’ve fought them if he had
been alive. Eventually the trio arrives at their destination, and while Jacob goes to the bathroom,
Klaatu asks Helen about his family. It turns out that the boy's father was a military engineer
and his mother passed away in childbirth. Helen married Jacob's father, but he also died and now
Jacob is under her care. Next, the trio enters a fast-food restaurant and Klaatu meets with Mr. Wu,
who is also an alien that took a human form and was sent to Earth seventy years ago to study
humanity. Mr. Wu explains he’s found humans to be destructive, stubborn, and unwilling to change,
and Klaatu agrees, so he tells Mr. Wu to leave because he’ll proceed with the operation. However
Mr. Wu intends to stay on Earth because during his research, he saw the bad but also the good,
and now he has a family of his own so he wants to spend his last moments with them. In the meantime,
the military installs super-strong protective panels around the inactive giant biorobot,
hoping this way they can block its powers. Their emergency hotline is drowning with hundreds of
calls from people who have seen Klaatu, so the alien is officially presented as a fugitive
criminal. Back to the trio, they are now heading for New Jersey. When they arrived in the woods,
Klaatu asks to stop the car and leaves, so Helen tells Jacob to wait while she follows him. As she
enters the woods, a swarm of weird insects flies past her, and she follows them to a lake where
Klaatu is looking at the water. Suddenly another glowing orb emerges from the lake and Klaatu
initiates the emergence protocol, which activates every single alien sphere that has landed all over
the planet. A shocked Helen returns to the car, and Jacob can sense something wrong. He fears
that Helen will marry Klaatu and he’ll take his father's place, but he doesn’t hear Helen when
she denies it and he runs into the woods. Helen follows him and suddenly they notice a bright
beam of light among the trees. It is the glowing sphere, which now is leaving the planet together
with all the others. The only sphere that remains on Earth is the one in which Klaatu arrived.
Speaking of Klaatu, he returns from the forest and tells Helen to take him back to the city,
but Helen refuses to help him until she gets an explanation. Klaatu tells her that mankind is
destroying the Earth, and since there aren't many planets in the universe where complex biological
organisms can live, Klaatu has come to save Earth from the humans, believing that the planet can be
reborn if all the human infestation is removed. Helen is appalled and tries to convince Klaatu
that humans can change so they should get another chance, but Klaatu doesn't believe her because
they’ve been watching humanity for years and change never came, now the situation has reached
a tipping point. Besides, the process has already begun and nothing can be changed. At that moment,
a policeman drives by and stops as soon as he recognizes the wanted man. He pulls a gun out
and tells them to surrender, causing Jacob to ask Klaatu not to hurt the cop. However Klaatu says
that his pain will be short and with a flick of his hand, he pushes Helen's car at the policeman,
crushing him. Jacob freaks out, but Klaatu quickly connects his powers to the car and revives the cop
using the vehicle’s energy as a defibrillator. Klaatu explains that he didn't intend to harm
the guy, he just wanted to remove a temporary obstacle. Helen is still convinced that Klaatu can
stop everything if he wants to, so she proposes to take Klaatu to a man who will change his mind.
Meanwhile the secret services are researching the various spheres that left Earth. Through
video footage, they discover the glowing orbs are transporting many kinds of Earth creatures away
into space. Regina realizes the spheres are arks like Noah's, meaning a flood is coming soon. While
the military places the biorobot in a silo deep underground, riots begin to break out all over the
planet and looting increases. Back to Helen, she brings Klaatu to see Karl, a Nobel Prize-winning
scientist she’s worked with. When Klaatu finds a formula on a board, he decides to correct it,
and Karl quickly joins him to solve the unfinished problem together. This allows Karl to guess Klaatu
is the wanted alien. In another room, Jacob watches tv and sees the hotline number to call in
case anyone has seen Klaatu. In the living room, Karl wonders how Klaatu’s civilization managed to
survive, and Klaatu explains that their sun began to die out and they had to evolve to survive. Karl
points out that was a case of change coming when a being is on the brink of extinction, and since
humans are at that point now, they should be given some more time. This gives Klaatu a lot to think
about, but their chat is suddenly interrupted by the appearance of air force helicopters. Klaatu,
Helen, and Jacob leave Karl's house in a hurry, and on their way out, Karl tells Helene to change
the alien's mind not by argument, but by action. The trio tries to hide from the military in the
woods, but Jacob steps out into an open clearing to begin shouting and waving his arms to attract
the attention of the helicopters before confessing to Helen that he called them because that is what
his father would have done. A devastated Helen tries to remind him that his father is no longer
around, but this only makes the boy cry. Suddenly one of the helicopters captures
Helen and immediately flies away. The other two helicopters spot Klaatu and prepare to open fire,
but Klaatu uses his powers to stun the pilots and make the helicopters crash into each other.
A terrified Jacob runs into the woods to escape, however Klaatu quickly catches up to him and saves
him just in time from falling into the river. Then Klaatu convinces the kid to follow him. Moments
later, Helen meets with Regina and asks her to let her go, explaining that Klaatu listens to
her and only she can stop him, but Regina refuses. Meanwhile the special forces are experimenting on
the giant biorobot at the military base. They try to pierce its armor, only for the diamond drill
to break. While the technician grabs another one, inside the cracks of the broken drill there are
weird insects multiplying at an insane rate and eating the drill. Suddenly the giant robot begins
to disintegrate into tiny little particles, which turn out to be bug-like nanorobots that instantly
begin devouring everything around them. As the windows crack, some of the men want to escape,
but the base has been sealed and now they can only wait. Soon everyone is turned to dust as the base
is completely destroyed. The military reports back to Regina about the situation, explaining
that the nanorobots are impossible to destroy. The missiles launched at them only increase the number
of the alien bugs, and now that they’ve broken out, they have formed a huge cloud that moves
in all directions and destroys everything in its path. Even a huge stadium turns to dust in seconds
when the bugs reach it. Finally realizing there’s nothing they can do, Regina releases Helen so she
can talk to Klaatu, and Michael will be going with her. In the forest, Klaatu brings Jacob
to a woodsman's cabin and lets him call Helen’s cell phone. Once they’ve agreed on a safe place to
meet, Jacob and Klaatu start making their way out, and Jacob admits that he no longer wants Klaatu
dead. This makes Klaatu question his beliefs about the nature of humanity. Moments later,
they arrive at the cemetery where Jacob’s father is buried, and he desperately asks Klaatu to use
his resurrecting power as he did earlier with the patrolman. However Klaatu’s powers have a
limit and there’s nothing he can do for a rotten body. Furious, Jacob tells Klaatu to leave, but
at that moment Helen shows up and runs to the boy to hug him tightly, trying to comfort him. Jacob
finally comes to terms with his father’s death, and he and Helen apologize to each other for their
recent behavior, agreeing to be a proper family from now on. Seeing such an emotional moment
convinces Klaatu that humanity has a positive side and that humans deserve another chance. To do so,
they need to change themselves and their way of life, and when Helen promises they will, Klaatu
watches the nanorobots and says he’ll try to stop them. The cloud of nanorobots is quickly taking
over New York City and eating up everything in their path, no matter if it’s people, buildings,
or vehicles. Regina talks to the president of the United States, explaining they’re trying to solve
this through peaceful negotiations. However the president is desperate and orders her to resume
military action. Helen, Jacob, Klaatu, and Michael rush back to New York where the remaining sphere
is. All streets are empty except for the military blocking the roads, but Klaatu makes Michael drive
right through them. At first the soldiers begin chasing them, but soon they receive orders to stay
back. Seconds later, the group makes it to Central Park and is surprised to see all the military and
scientists are gone. At that moment, the air force begins bombing the area like the president wanted,
causing the car to flip and crash while a huge fire begins engulfing the park. Unfortunately
Michale dies, but the others are ok. The nanorobots arrive at the area and begin
cracking up the car, so Klaatu takes Jacob and Helen out, intending to reach the sphere.
However the bug cloud is already surrounding the globe and covering the sky, so the trio has to
run to hide under a bridge. Suddenly Jacob’s nose begins bleeding and he passes out as Helen’s nose
begins bleeding as well. Klaatu explains they’re dying because the bugs are slowly eating them
from inside, so Helen begs for his help. The alien grabs their hands and uses his powers to make the
bugs come out, absorbing them into his own body instead. While Jacob wakes up, Klaatu confirms
Karl was right, humans are capable of change when on the edge of the abyss. After giving the family
a goodbye look, Klaatu steps outside and slowly forces his way through the cloud of nanorobots
until he reaches the sphere. Then he touches the glowing orb, which results in his body
disintegrating but also the destruction of all the nanobots. As the dead bugs fall on all over the
planet, all technology also goes out of commission and cities are plunged into darkness, which is the
price humanity must pay for what they’ve done to Earth. Helen and Jacob come out to watch
the glowing sphere leave their planet, and Jacob implies that Klaatu’s essence is still inside.