In 2005, scientists find a planet with a climate nearly identical to Earth's, which means it could sustain life. In 2006, NASA builds the most powerful transmission device and starts the Beacon Project. A special observatory is built in Hawaii, which will send out a message on signals. A satellite that orbits Earth every 24 hours will amplify those signals and send them to the new planet, hoping to get an answer from extraterrestrial life.
Meanwhile, Alex is celebrating his birthday at a bar with his brother, Commander Stone, who wants Alex to join him in the Navy. Alex refuses and Stone goes to flirt with Samantha, who keeps asking for a burrito, but the kitchen is closed. Determined to impress her, Alex runs to the store to get a burrito, but the place is closed, too.
He ends up climbing on the roof and falling inside when a ceiling panel breaks. After taking a burrito and heating it up, Alex drops some money on the counters and uses a ladder to escape. However, he falls and damages lots of products. Seconds later, the cops are chasing Alex through the street. He manages to give the burrito to Samantha before he's tased down.
The next morning, Stone scolds Alex for getting in trouble. To make matters worse, Samantha is the daughter of an admiral, so Stone could get in trouble at work, too. Stone rants about his brother having no job and no sense of responsibility before announcing that he's forcing Alex to join the Navy. Sometime later, an event known as Rimack is held in Hawaii.
Dozens of ships arrive to run the world's largest maritime warfare exercise, which is supposed to promote collaboration among countries. Before the actual exercise, they play a mini soccer tournament. Alex has become the leader of the American team and is now dating Samantha. During the finals against Japan, Alex gets kicked in the face and given a penalty.
Stone points out he's concussed and another player should kick, but Alex yells at his teammates and does it himself. He kicks very badly and Japan wins the match. That night, Alex promises Samantha that he'll ask her father for permission to marry her, even if he thinks it's an obsolete tradition. Meanwhile, the signal sent by the Beacon Project finds something in space.
The next day, Admiral Terrence gives a speech during the opening ceremony. Alex is late and sneaks around to join his team on the ship, which is definitely noticed by the higher-ups. During the afterparty, Samantha convinces her dad to give Alex 5 minutes to talk, but it's clear that Terrence doesn't like him. A very nervous Alex goes to the bathroom to practice what he'll say and is mocked by Nagata, the player who kicked him.
An argument ensues and ends in a fight. Seconds later, they're in Terren's office pretending they just had an accident, but Terrence doesn't believe them and scolds them both. Then Terrence asks for a moment alone with Alex to tell him he's wasting his abilities and Samantha could have better. The first day of the event goes well and everyone gets to show off their teamwork while directing the vast number of ships, planes, and helicopters.
That night, Stone confirms that Alex will be kicked out after the exercise ends. The following day, Samantha continues to work as a physical therapist. She's assigned to Mick, a former colonel who lost both his legs during combat duty. He's been very depressed since then, so Samantha takes him on hikes and tries to teach him a new way to look at life.
Meanwhile, a huge object flies past Jupiter and splits into five pieces. The Department of Extraterrestrial Contact notices this on their radars and immediately calls NASA, the Air Force, and the Beacon Project. The objects are flying in formation and coming straight to Earth, which means they're intelligent spaceships and not just random asteroids.
One of these ships crashes into a satellite and splinters off from the group as it falls apart. The four spaceships fall in the Pacific Ocean, which is seen by Samantha and Mick from the hills. The broken ship crashes into Hong Kong, destroying multiple buildings and killing thousands of people in the process. The falling debris kills thousands more as they try to run away.
Soon, the technicians confirm that the ships came from the new planet, which means they're responding to the signals sent by humans. All the ships in Hawaii pause the exercise and start searching for the ships in the ocean, although they don't appear on their radars. Chinese scientists sample the broken ship and discover it's made of an unknown material.
Its grid patterns appear to be a communication unit. A few hours later, the ships in Hawaii see something strange on the water, but it still doesn't show up on their radars. A boat approaches the spaceship and tries to make contact, but they get no answer. Alex jumps on the metal and nothing happens. So, he then tries to touch the main structure only for an electric shock to send him flying.
While Kora rushes to rescue him, the spaceship charges some energy and shoots two beams into the sky. This creates a force field around the area, trapping half of the fleet inside. Those inside the field can't communicate with the outside world and their radars start failing. A fighter jet tries to fly through the force field and explodes on contact.
Suddenly, the spaceships come out of the water, proving to be huge and very advanced. When Stone sounds his ship's horn as a warning, a spaceship responds with a powerful shock wave that breaks every window and hurts people's ears. Then, the Navy shoots a warning missile that causes no damage. The alien ship responds with missiles of its own, so the soldiers start shooting to destroy them in the air.
Unfortunately, a missile still lands on a ship and explodes, causing severe damage and killing a few men. On the boat, the team moves around the spaceship with open fire while dodging the attacks coming after them. Stone orders fire from the main ship, too, but their locking systems are broken because of the shock wave, and the attack isn't very effective.
The spaceship shoots back at them, and once again, the soldiers can't stop every missile. One explodes on the ship, killing several men and making a hole that floods the hall. A desperate stone orders his men to keep up the fire, but the enemy retaliates with a bigger attack and the entire ship explodes. After watching his brother die, Alex sends the boat back to the fleet.
He learns that all the superior officers died during the attack, so he's the next full senior and therefore in charge. Eager for revenge, Alex tells the crew to get ready for a full attack. On the Japanese ship, Nagata orders his men to provide backup. The aliens immediately shoot back and disable Nagata's ship with a big explosion. Alex wants to keep fighting, but his crew makes him see reason.
So, they turn around the ship and go to rescue the Japanese soldiers from their sinking vessel. In the absence of a threat, the spaceship puts away its cannons. However, the main alien structure charges again and sends out a bunch of shredding machines together with a smaller aircraft. Two shredders land on Hawaii's military base, destroying every building, jet, and helicopter on their path.
Another shredder lands in town, interrupting a baseball game. It stops in front of a child, but ignores it. Instead, it goes after other machines and structures like bridges, causing cars to fall into an abyss. On the hills, Mick and Samantha see the smaller aircraft fly by. The police finds them and tell them to leave the area, but Mick stays because he wants to see the aliens.
The aircraft lands next to the observatory and the pilot comes out to analyze the structure. When the police cars appear on the road, a strong shock wave stops them and the pilot attacks them. While rescuing the Japanese men, the crew finds the alien pilot who fell from the satellite crash. They remove the helmet to take a closer look, only for the alien to wake up and grab Alex's face.
This makes him see a vision of these aliens attacking and conquering tons of planets around the universe. Suddenly, an explosion hits the wall and knocks everyone down. Through the hole in the wall, alien soldiers enter the ship and take their pilot before leaving. Alex hears on the radio that two men went down in another sector, which means an alien stayed behind for sabotage.
The ship is locked down and a search begins. When a soldier takes the stairs, he's suddenly pulled up and thrown across the corridor. In the room with the weapon systems, the door is suddenly kicked off and the alien comes down. It ignores the technician and proceeds to scan the weapons. When the man tries to stop it, the alien easily throws him at the wall.
Then the technician starts attacking the alien with a tool only to be easily overpowered and thrown again. At that moment, Alex comes in with open fire, but his bullets do nothing to the armor. While the alien is busy attacking him, Kora appears behind it and also starts shooting with multiple weapons. However, the alien easily disarms her and brings her down.
Alex sends her to the weapon controls before he rushes outside to bait the alien into following him. Cora moves the cannon and Alex jumps to hide over the railing as the shot finally kills their enemy. On the hills, Mick and Samantha find the destroyed police cars. After Samantha takes the keys from a body, the duo sees the aliens coming and rushes to hide.
Thankfully, the aliens think the noises came from the horses and leave. Then Mick gathers some weapons while Samantha tries to use the radio from the only standing car. Suddenly, they're approached by Cal, the employee from the observatory. He explains the aliens took over the building and are trying to use Earth's satellites to reestablish communications with their home planet since their comm's vessel was the one that crashed.
If they're successful, a whole extraterrestrial army will come to Earth. Meanwhile, the media finally receives authorization from the government to announce that aliens are invading and various leaders tell people to stay calm. However, the general population still panics and riots begin spreading on the streets.
Back on the ship, a soldier puts on the alien's helmet and notices it's very similar to sunglasses. He also remembers that the alien had the same eyes as a lizard. He concludes that just like lizards, the aliens are weak to sunlight and the armor is protecting them. The crew starts discussing ideas on how to use this information, which is hard because their radars can't detect the aliens.
Nagata points out that the aliens don't see humans either. They only react to direct attacks. He thinks they can use weather buoys to replace the radars because they can measure water displacements which the spaceships cause every time they move. The technicians access all the buoys in the area and manage to chart an entire map.
Alex is so impressed that he puts Nagata in charge of the operation. The team keeps an eye on the chart and finds a spaceship as soon as it moves, allowing them to act fast and open fire. Unfortunately, the shot misses and the spaceship starts moving toward the fleet. Seeing another spaceship fly by, Samantha wishes she could contact Alex to tell him about the observatory.
Cal explains that the aliens are blocking their calms using a jamming pulse, which means it isn't a total wall and it may have gaps that may allow for a message to be sent into the force field. To do so, he needs a device that was left in the observatory. Mick forces a terrified Cal to retrieve it.
Cal carefully sneaks around by crawling on the ground in the dark and enters the observatory through the back door. After he grabs his device, an alien appears behind him and touches the metal, but it can't see Kal himself. This allows him to run away and reunite with his friends. Alex's ship launches another attack that also misses, and this time the aliens shoot back.
Thankfully, the ship manages to dodge or shoot down the missiles, although the explosion does shake the ship. Now that the spaceships are so close, the human's next attack manages to hit and they bring two vessels down. At that moment, Samantha manages to contact the ship. She tells Alex that the aliens will make contact with their planet in 4 hours, so they have to destroy the observatory before time runs out.
Alex tries to ask for more details, but the call is cut short. Then the team notices abnormal water displacements on the buoys. It appears the spaceship is jumping all over the place to trick them. Alex gets an idea and orders the men to get the weapons ready. During the rest of the night, the ships move toward the island and stop there in the morning.
When the spaceship approaches them, they wait for the sun to rise and open fire to break the windows. The sunlight immediately blinds the aliens and the soldiers send out the missiles to blow the spaceship up at impressive speed. Suddenly, the shredders come back and start destroying Alex's ship, killing soldiers and causing many explosions.
A man is stuck in a hallway, but before he can get killed, too, Kora drags him out of the way. As the ship begins to sink, the crew jumps into the sea to save themselves on the lifeboats. Alex and Nagata rely on each other to climb to the last standing part and manage to jump right before the ship explodes. Seeing this from the hills, Samantha and Mick decide to head to the observatory, but Cal chooses to stay behind.
The soldiers on the lifeboats feel defeated, but Alex says they can use a decommissioned battleship that is being used as a museum. They go aboard and discover the systems are outdated, so all the firing is manual. They don't have enough people or experience to use them. Thankfully, the retired soldiers who attended the event come to the ship ready to help.
Both crews work together to get rid of all the decorations, get the systems running, and do any necessary repairs. The ship takes off and notices the alien structure shooting those beams again. This time it rises from the water and transforms into a battle machine with numerous weapons ready to shoot. Alex makes Cora point the guns towards the side and the ship starts making a turn.
When the aliens open fire, Alex orders the anchor to be dropped. The ship stops moving and the enemy's missiles fall into the water. Then the humans start working fast to shoot as many weapons as possible, damaging the spaceship little by little. The aliens shoot back and cause some damage, but it's not enough to sink the ship.
The crew keeps up the fire and finally destroys the spaceship, including the device that is keeping up the force field. This allows the other half of the fleet with Terrence to join the battle. At that moment, the aliens in the observatory send out the message and a light beam reaches the sky. Mick and Samantha show up in the cop car and start driving through the electrical connections until they crash.
This is enough to stop the transmission, but now Samantha and the gun are stuck in the car. When an alien approaches, Mick tackles it and starts a fight. The alien loses the helmet in the process and the sunlight blinds it, giving Mick the advantage until the alien brings him down.
When the creature is about to kill him, Cal reappears and hits it with his device. Then Mick chokes the alien to death while Cal helps Samantha. The trio runs away as other aliens reconnect everything to send out the message again. On the ship, the crew works together to move a special missile that will destroy the observatory. The destroyed spaceship gets more Shredders ready, and since the humans only have one shot left, the crew thinks they'll die with their last attack.
The missile is shot and blows up the observatory, killing all the aliens in the area and stopping the message permanently. When the Shredders are about to destroy the battleship, the jets finally arrive and shoot them first. The jets also shoot any remnants of the main spaceship, ending the battle at last. Sometime later, the entire crew and Mick are given medals of honor.
Fallen soldiers like Stone are recognized as well. Terrence promotes Alex to commander and gives him his own ship to lead. After the ceremony, Alex finally asks Terrence for his blessing. Parents says no, but then reveals he's joking and invites Alex to have a burrito for lunch. Meanwhile, in Scotland, three boys notice a destroyed building and find a piece of the alien ship.
They call a technician to cut it open and discover a living alien inside.
