• Aliens and their Guardians are hiding on Earth from intergalactic bounty hunters. They can only be killed in numerical order, and Number Four is next on the list. This is his story.

  • Extraordinary teen John Smith (Pettyfer) is a fugitive on the run from ruthless enemies sent to destroy him. Changing his identity, moving from town to town with his guardian Henri (Olyphant), John is always the new kid with no ties to his past. In the small Ohio town he now calls home, John encounters unexpected, life-changing events - his first love (Agron), powerful new abilities and a connection to the others who share his incredible destiny.

  • High school senior John Smith, just moving into the small town of Paradise, Ohio, with his "father" Henri, is outwardly your typical American teenager; however, John (which is just his latest assumed name) is in reality a refuge from the planet Lorien. When he was but an infant, he and eight other Lorien infants escaped from Lorien's holocaust when the planet was overrun by the marauding Mogadorians, who killed all the other Loriens. Each of the nine was assigned a protector/warrior, John's being Henri. The nine are all on Earth, but each has no idea the whereabouts of the other eight. The Mogadorians are out to find and kill the nine, in order, with John being number four. The death of number three, which John felt, prompts his and Henri's move to Paradise, knowing he will be next. Although aware of his heritage, John only knows life on Earth as his true history; thus, he has many of those wants of the American teenager. Their move to Paradise coincides with John beginning to understand he has special powers, which made him one of the chosen nine. Although Henri tells John to stay under the radar, John has a less than inauspicious introduction to life in Paradise, largely because of his associations with two classmates. There's Sam, an oft-picked-upon boy, who, largely because his long-missing father, has always believed in extraterrestrial life (passed down from his dad); and, there's Sarah, the first girl to whom John has ever been attracted. The issue with Sarah is that she is the ex-girlfriend of Mark, the football team's quarterback and school's chief bully, who still wants Sarah back despite having bad-mouthed her publicly since their break-up. John's notoriety in combination with the problems of dealing with the regular issues of teenage life may make John and Henri easier to find by the Mogadorians, which places the lives of all those in Paradise in danger. All the while, Henri continues with his other primary mission, which is to help John find the remaining five, who in combination can better battle the Mogadorians.

  • John Smith tries his best to play the nondescript high school senior who's just moved to a small mid-Western town in Ohio with his single-parent dad, Henri, but maturity ushers in the onset of extraordinary powers that are John's birthright as one of the very few individuals who escaped the genocidal rampage of the Mogadorians, an alien race that destroyed the inhabitants of Lorien, the planet where John was born. A total of eight infants escaped to Earth, each accompanied by a warrior to serve as their guardian and protector. The Mogadorians' quest to destroy the last of the Loriens has led them to Earth. Three of their targets have already been eliminated. It becomes John's task to find and join with the remaining members of his race before he becomes victim number four.

  • A teenage fugitive with an incredible secret races to stay one step ahead of the mysterious forces seeking to track and destroy him in this action thriller from director D.J. Caruso (Disturbia, Eagle Eye). With three dead and one on the run, the race to find the elusive Number Four begins. Outwardly normal teen John Smith (Alex Pettyfer) never gets too comfortable in the same identity, and along with his guardian, Henri (Timothy Olyphant), he is constantly moving from town to town -- the perpetual new kid in a series of strangely familiar schools. Despite the fact that his nomadic lifestyle has made it difficult to form meaningful connections, John experiences the joy of first love with a beautiful young woman (Dianna Agron) and begins to unlock his full potential after arriving with Henri in a small Ohio town. With each passing day, John gains a stronger grasp on his extraordinary new powers, and his bond to the beings that share his fantastic fate grows stronger.

An alien from planet Lorien (Alex Pettyfer) was sent to Earth as a child alongside eight others to escape an invading race, the Mogadorians, which destroyed their home planet. He is protected by a Warrior/Guardian called Henri (Timothy Olyphant) and has developed superpowers due to his extraterrestrial nature, such as enhanced strength, speed, agility, telekinesis, resistance to fire and heat, and the power to generate light from his hands.

The Mogadorians, led by the Commander (Kevin Durand), know about the nine toddlers that came to Earth and search for them. The nine gifted Loriens can only be killed in numerical sequence, with three of them having already been slain. John is Number Four. Knowing this, he and Henri flee Florida to Paradise, Ohio, where John befriends conspiracy theorist Sam Goode (Callan McAuliffe), a dog he names Bernie Kosar, and amateur photographer Sarah Hart (Dianna Agron), whose ex-boyfriend, school athlete Mark James (Jake Abel), is a bully who often torments Sam and now John.

During the spring carnival, Mark and his football cohorts accost John and Sarah, whom they believe are in a relationship, following them into the woods where they attempt to beat John up; however, John uses his powers to fend them off and rescue Sarah. Sam witnesses the events, and John, later confronted, reveals his true origin to him. Shortly thereafter, Mark's father, the local sheriff, interrogates Henri on John's whereabouts during his son and hospitalized friends' attack, noticing Henri's high-tech surveillance system.

With John's random displays of power (caused by his difficulty in controlling them) and too many people getting suspicious, Henri tells John they must move on, but John can't disappear just like that. He's fallen for Sarah in the Lorien mate-for-life kind of way.

As the Mogadorians close in on John, another Lorien alien, Number Six (Teresa Palmer), hunts down the Mogadorians herself instead of running (a proactive decision after the murder of her Guardian). The Mogadorians eventually locate John and manipulate two conspiracy theorists into capturing Henri. When John and Sam go to rescue him, they are attacked but manage to fend the Mogadorians off. Henri is mortally wounded and dies after John and Sam escape with him and some Lorien artifacts, including a blue rock fragment that'll act as a tracking device to locate other Loriens. Sam's father, a conspiracy theorist who disappeared while hunting aliens in Mexico, had another. While Sam searches his home for it, John tries to say goodbye to Sarah at a party, only to discover that the Mogadorians have framed him and Henri for the murders of the conspiracy theorists, getting them additionally labeled as terrorists due to their suspicious use of cutting-edge technology. Mark sees John and calls his sheriff father, who corners John and Sarah. In saving Sarah from an accidental fall, John reveals his powers in the process. The two escape to their high school.

The Commander and his goon squad, having arrived in Paradise, block the exits with trucks. He confronts Mark and his father and, after injuring the latter, physically forces the former to show him where John is hiding, whereby Mark takes them to the school, knowing it's Sarah's usual hideout.

There, John, Sarah, and Sam are attacked by the Commander and his soldiers, who have brought two giant monsters to hunt down the trio. They are saved by the arrival of Number Six and John's "dog" Bernie Kosar, who reveals his true form as a good Chimera, which can shape-shift (sent by John's parents to protect him further). John, Bernie Kosar and Number Six (who can make herself invisible and block energy-based attacks) fight the Mogadorians. They eventually defeat them all, including the Commander, whose energy grenades are overheated by John and explode, destroying his body.

Bernie Kosar eventually shifts back into beagle form, bloodied and alive but favoring a very wounded paw.

On the following day, John, Number Six, Sam, and Bernie Kosar, the shape-shifting Chimera, unite their blue rocks and discover the location of the other four surviving Loriens. They set off to find and rally them together to protect Earth from the Mogadorians, leaving Sarah and a repentant Mark (who has redeemed himself by lying to his father about John's whereabouts and returned Henri's personal Lorien box to John) behind.