The Australian box-office hit "Tomorrow When the War Began" begins by following the same template as Neil Marshall's 2005 British horror classic "The Descent" and dozens of thrillers before it. You know the drill: A small group of unsuspecting adventurers wanders into danger, and not all of them will get out alive.

In this case, it's a group of seven (later eight) impossibly attractive teenagers from the small coastal town of Wirrawee. They appear to have been hand-picked from a glamour-mag photo shoot (except for the brainy girl, the movie's answer to "Scooby Doo's" Thelma), but this time they're not spelunking and being eaten by cave-dwelling freakazoids. Instead they're hiking in a remote, breathtakingly beautiful Australian forest nicknamed "Hell," unaware that their homes, families and futures have been torn apart by a sudden, violent invasion of mysterious military forces.

Based on John Marsden's popular "Tomorrow" series of Australian young-adult novels, "Tomorrow When the War Began" is essentially a World War III thriller for the "Twilight" crowd, in which our fashionable, ridiculously outnumbered heroes instantly develop amazing survival skills and rise up to fight the enemy. That includes the laid-back stoner who joins them later. Enemy invasion? Dude, what a buzzkill.

After writing a string of high-profile screenplays, including Michael Mann's "Collateral" and "G.I. Joe: The Rise of Cobra," first-time director Stuart Beattie delivers a few knockout action sequences that are refreshingly devoid of computer-generated enhancements, but his lazy, frustratingly unintelligent script is a marvel of narrative ineptitude. Loaded with convenient shortcuts and unanswered questions (perhaps to make room for sequels?), it's a mess of uninteresting mayhem that plays like the lackluster pilot of a formulaic TV series.

The kids are appealing enough as they enjoy their preinvasion bonding, but as Beattie pushes them through a series of increasingly unconvincing battle scenarios, you have to wonder if he believes his own movie. If so, he's either in denial or very gullible.

Information in this article, originally published Feb. 23, 2012, was corrected Feb. 24, 2012. A previous version of this story referred to "The Ascent" as an Australian film, but the film is British.