Plot

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.—Walt Disney Pictures

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.—Huggo

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.—- written by: R. Merriman <wyldberi@msn.com>

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, Henri (Timothy Olyphant), and has developed superpowers due to his extraterrestrial nature, such as enhanced strength, speed and agility, telekinesis, resistance to fire and heat, and the power to generate light from his hands.

The Mogadorians, led by the Commander (Kevin Durand) eventually discover about the nine toddlers and come to Earth in search of them. These Loriens can only be killed in a particular sequence, with three of them having already been slain. John is Number Four. Knowing this, he and Henri move from Florida to Paradise, Ohio, where John befriends conspiracy theorist Sam Goode (Callan McAuliffe), a dog named Bernie Kosar, and falls in love with amateur photographer Sarah Hart (Dianna Agron) who is in his class at Paradise high school. Sarah's ex-boyfriend, school athlete Mark James (Jake Abel) is a bully who often torments both John and Sam.

Henri keeps a box given by John's father when they were escaping the planet. Henri treasures the box above everything else & has promised to give it to John, when the time is right. Henri reveals to John that John was chosen by Lorien's as a guardian & thus has the special powers which he has inherited from his parents.

Sam tells John that his dad was a conspiracy theorist & who has now been missing for many years. He worked at the Paradise steel plant & was building some sort of a landing platform for alien craft, at the time of his disappearance in New Mexico. We see that Henri is checking out internet reports on Sam's dad at home. Henri even investigates at the abandoned steel plant, where Sam's dad used to work, & finds the shell of a blue rock in a secluded and hidden spot.

During the spring carnival, Mark and his friends capture John and Sarah, whom they believe are in a relationship, and follow them into the woods, where they attempt to beat John up. However, he uses his powers to fend them off and rescue Sarah. Sam witnesses the events, and John tells him his true origin. Shortly thereafter, Mark's father, the local sheriff, interrogates Henri on John's whereabouts when his son and his friends were attacked, and notices that Henri has a high-tech surveillance system.

Henri tells John that too many people are suspicious of them, in addition to Johns random displays of power, caused by his difficulty in controlling them, and that they must leave. However, John tells him he can't because he's in love with Sarah. Henri attacks John & John fights back & almost beats Henri. Henri explains that John was saved for a higher purpose, to defeat the Mogadorians. Very few Loriens can, & John is one of them. The next day, Henri gives John his father's box. The Mogadorians start searching for John. Another alien from Lorien, Number Six (Jake Abel), decided to go after the Mogadorians instead of running away from them after her Guardian was murdered.

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 Mogadorians off. However, Henri is mortally wounded and dies after John and Sam escape with some Lorien artifacts, including a blue rock that acts as a tracking device to locate other Loriens. Sam's father, a conspiracy theorist who disappeared while hunting aliens in Mexico, has another. While Sam searches 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, as well as being terrorists due to their cutting-edge technology. Mark sees John and calls his father, who corners John and Sarah. He saves her from a fall, revealing his powers in the process, and they escape to their high school.

Meanwhile, The Commander also arrives at Paradise, blocking the exits with trucks. He is confronted by Mark and his father, and, after injuring the latter, he forces the former to show him where John is hiding, Mark then takes him to the school, which he knows is Sarahs hideout.

There, John, Sarah, and Sam are attacked by the Commander and his soldiers, who have brought two giant monsters to hunt the trio. They are saved by Number Six and John's "dog," Bernie Kosar, who reveals his true form as a good Chimera, which can shape-shift, and was sent by his parents to protect him. Bernie Kosar eventually shape-shifts back to a beagle with a very wounded paw. John 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.

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 to find them 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 returning to John a box belonging to his father.