Here are the Cliff's Notes on "I Am Number Four": "Twilight" with aliens. Since space creatures don't arrive with the traditional back stories of vampires and werewolves, the story of extraterrestrial conflict and teenage longing requires a little setup. John Smith (Alex Pettyfer), a new transfer student to the high school in Paradise, Ohio, arrives with more than the usual adolescent baggage.

He is one of a handful of children surviving a space war. His ancestors, the people of Lorien, were all but exterminated by the evil Mogadorians. The remaining nine fled to Earth, where their Abercrombie & Fitch looks make them stand out while trying to blend in. The Mogadorians, a black-trench-coat Mafia with bald heads and tribal tattoos, are on their trail, out to finish the genocide. They already have killed Numbers One, Two and Three. Which means John is up next.

The film is based on the young-adult novel of the same name, which is based on Superman comics, "Terminator," the old "alien high" WB TV series "Roswell," "Harry Potter" and a certain bestselling series about folks with fangs in Forks, Wash. The result is a lot less mediocre than you might expect. Director D.J. Caruso ("Disturbia") aims for flashy fun and hits the target. The tone here is lighter than the heavy-breathing angst of the "Twilight" films. When John and his new earthling love move in for a long goodnight kiss outside her front door, her off-screen parents flick the porch lights on and off impatiently.

"I Am Number Four" bristles with nice touches like that while nimbly handling its storytelling chores. It manages to balance the telling of the tale with fierce attacks from the dastardly Mogadorians, equipped with plasma rifles and giant, jaw-snapping beasts. John and his mentor/bodyguard Henri (Timothy Olyphant) defend themselves with gymnastic evasive maneuvers and glowing blades that suggest junior varsity light sabers.

With the aid of a loyal mutt that proves surprisingly adaptable, an earthling sidekick with plenty of experience in E.T. lore and a mysterious newcomer who looks great in tight motorcycle leathers, John is well positioned to keep dodging Mogadorians for another half-dozen episodes. I'll be pleased to see "I Am Number Four 2."

Colin Covert • 612-673-7186