Director DJ Caruso (Eagle Eye, Disturbia) provides the requisite slam-bang thrills in this adaptation of Pittacus Lore’s novel, the first instalment of a proposed six-book series.

To a cynical eye, I Am Number Four has been constructed purely with box-office receipts in mind, mimicking the forbidden love and adventure of the Twilight films, albeit with earth-bound aliens replacing the vampires and werewolves.

Mulder and Scully wouldn’t blink twice at the central conceit of rival extra-terrestrial races fighting for survival among us.

The script follows the template of Spider-Man by creating a conflicted hero, who realises over the course of this opening salvo that his powers must be harnessed for good.

It certainly doesn’t hurt that leading man Alex Pettyfer looks good with his shirt off, to draw in the teenage girls.

However, it may hurt the prospects of a franchise that he can’t match the gym-toned physique with a similarly robust emotional performance, and unlike Robert Pattinson, he can’t blame lifelessness in front of the camera on his character being a member of the bloodsucking undead.

The film opens with a night-time chase through a jungle in Kenya, culminating in the grisly demise of a boy.

‘Number Three is dead,’ gasps 15-year-old John Smith (Pettyfer), who lives hundreds of miles away with his guardian Henri (Timothy Olyphant).

John looks like any other high school student but he is really an alien from the doomed planet Lorien, hiding on Earth from a destructive rival race called the Mogadorians.

These aggressive hunters intend to kill the Lorien refugees in a specific order, and since John is Number Four, he is next on their hit-list.

When the Mogadorians finally catch up with John and Henri, they escape to the quaint town of Paradise, Ohio, where John befriends students Sam Goode (Callan McAuliffe) and Sarah Hart (Dianna Agron), making an enemy of her jock ex-boyfriend, Mark (Jake Abel).

I Am Number Four maintains a brisk pace with regular set pieces, peppered with digital trickery and a smattering of bloodshed to justify the 12A certificate.

McAuliffe acts his co-stars off the screen as the sidekick who laments, ‘My entire childhood has been an episode of X-Files.’ Pettyfer copes with the physical rigours of his role and he makes an attractive pairing with Agron, who couldn’t be more adorably cute if she tried.

Plot strands such as the whereabouts of Sam’s father are left hanging as teasers for future films, and the climactic showdown neatly sets up intrigues and a potential love triangle involving a mysterious female assassin (Teresa Palmer) in the next chapter, The Power Of Six – a fair rating for a capable if disappointingly lightweight introduction to the Lorien universe.

• Release Date: Wednesday 23 February 2011
• Certificate: 12A
• Runtime: 109mins