The film was produced by Michael Bay through DreamWorks and released by DreamWorks through Disney's Touchstone distribution label. The Hollywood Reporter projected the budget to be between $50 and $60 million. The film was released in both conventional and IMAX theatres on February 18, 2011.
Plot
John Smith (Alex Pettyfer) is an alien from the planet Lorien. He was sent to Earth as a child with eight others to escape the invading Mogadorians, who destroyed Lorien. Here, John is protected by a Guardian, Henri (Timothy Olyphant), and has developed "legacies", including enhanced strength, speed and agility, telekinesis and the power to transmit plasma light through his hands.
The Mogadorians, led by the Commander (Kevin Durand) learn about the nine children and come to Earth to find them. The Loriens can only be killed in sequence; Number One through Number Nine, though, and three of them are already dead, with John being Number Four. Knowing this, he and Henri move from a beachside bungalow in Florida to an old farm in Paradise, Ohio, where John befriends conspiracy theorist Sam Goode (Callan McAuliffe) and a dog which he names Bernie Kosar. He also falls for an amateur photographer, Sarah Hart (Dianna Agron). Her ex-boyfriend, football player Mark James (Jake Abel) is a bully who torments both John and Sam.
During the Spring Fair, Mark and his friends chase Sarah and John into the woods, where they try to beat John up. However, he uses his legacies to fend them off and rescue Sarah. Sam witnesses this and how he'd used his legacies. John reveals his true origins to Sam. The next day, Mark's father, the local sheriff, interrogates Henri on John's whereabouts when his son and his friends were attacked.
Henri tells John that too many people are suspicious of them so they have to leave. John refuses because of Sarah. Meanwhile the Mogadorians continue searching for John, while being trailed by another Lorien, Number Six (Teresa Palmer) who is also trying to locate Number Four. Number Six's guardian was killed, and she realizes that the remaining six of the Lorien Garde will have to team up and fight against the Mogadorians. She knows Number Three is dead and that Number Four is being hunted.
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. However, Henri dies after John and Sam escape with some Lorien artifacts, including a blue rock that acts as a tracking device for other Loriens. Sam's father, a conspiracy theorist who disappeared while hunting aliens in Mexico, had another of the rocks. 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. Mark sees John and calls his father, who corners John and Sarah. John saves Sarah from a fall, revealing his powers in the process, and they escape to their high school.
Meanwhile, The Commander arrives in Paradise, in a convoy of trucks. He is confronted by Mark and his father, and after injuring the sheriff, he forces Mark to show him where John is hiding. Mark takes him to the school, which he knows is Sarah's hideout.
There, John, Sarah and Sam are attacked by the Mogadorians, who brought two giant monsters to hunt the trio. They are saved by Number Six and Bernie, who is actually a shapeshifting Chimera sent by John's biological parents to protect him. John and Number Six, who can teleport and can block energy attacks, continue to fight the Mogadorians. They eventually defeat them all, including the Commander.
The following day, John and Number Six unite their blue rocks and discover the location of the other four surviving Loriens. John decides to let Sam come with them in hopes of finding Sam's father. They set off to find the others so they can all protect Earth from the Mogadorians, leaving Sarah and a repentant Mark, who lies to his father about John's whereabouts and returns a box left to John by his Dad that was in police evidence.
John leaves after promising to return to Paradise and to Sarah.
