For all the technical accolades and financial spoils showered upon James Cameron’s Avatar, there remains one inconvenient truth that’ll forever hinder the film’s legacy: Cameron’s script for the record-setting blockbuster is just too damn generic. Rather than push the storytelling in the same ways as he did the production’s effects work, Cameron seemingly devoted less attention to the writing and basically cranked out Dances With Wolves: The Ferngully Edition. The same exterior-over-interior issue pervades the man’s latest project, Sanctum, which Cameron executive produced. Well shot and immersive in setting, the cave-diving-gone-wrong adventure flatlines due to a pedestrian screenplay and bottom-of-the-barrel acting. Much like Avatar, Sanctum looks great yet feels lifeless.

Sanctum - Father and SonInstead of Dances With Wolves, Sanctum brings to mind Neil Marshall’s great 2005 horror film The Descent, minus any cave-dwelling, and homicidal, bat-like humanoids. A group of underwater divers heads into the South Pacific’s Esa-ala Caves, hoping to conquer one of the world’s most notoriously dangerous underground terrains. The crew is led by Frank Maguire (Richard Roxburgh), a highly respected diving expert who’s both fearless and stubborn. Under his watch are his teenage son, Josh (Rhys Wakefield), his financier, Carl (Ioan Gruffudd), and a handful of poorly developed and interchangeable colleagues with no distinguishing characteristics. While within the Esa-ala’s depths, a massive storm floods the caves, trapping the team beneath the surface and setting into motion your basic survival-against-insurmountable-odds tale.

If simply read on paper, the plot sounds like a no-brainer. Claustrophobic intensity is all but guaranteed, and the fact that Sanctum was shot on location in Australia lends authenticity to the action. And Australian director Alister Grierson takes full advantage of his surroundings, capturing wide-angle shots of the vast scenery to drive home the hollowness and escape-free reality of the caves. As a National Geographic-like display, Sanctum is at times breathtaking in its scope. Shot using the same 3D photography tricks employed by Cameron for Avatar, Grierson’s landscape pops without distracting; it’s subtle 3D, without any random objects flying toward the eyes for gimmick’s sake (the eyeball in 2009’s My Bloody Valentine, for example, or Jerry O’Connell’s bitten-off schlong in last year’s Piranha 3D).

Sanctum - Ioan GruffoddVisual panache can only carry a movie so far, though, unless it’s an unstoppable juggernaut like Avatar, and Esa-ala is no Pandora. Sanctum’s script—written by John Garvin and Andrew Wright—sacrifices imagination for groan-inducing dialogue (“We’re bits of dust passing through.”) and anonymous plot-movers. Only three of the many characters are even partially groomed, and one of them, Gruffodd’s master complainer, is embarrassingly mishandled. It doesn’t help matters that Gruffodd, known from the subpar Fantastic Four movies, couldn’t act his way out of a high school drama club; over-exaggerating lines that are already awful, his is a performance unintentionally fit to elicit in-theater laughter. As the father and son, Roxburgh and Wakefield simply go through the motions, rendering the film’s supposed backbone (the love between a hard-nosed dad and his rebellious yet love-seeking son) a non-factor. By Sanctum’s barely attention-holding final act, which is where the action really attempts to take over, the conflicts between Gruffold’s third-act-villain and the daddy/kid pair transpires like a comedy of errors. The only way Grierson could’ve salvaged the low-stakes finale would’ve been to sic’ those creatures from The Descent on his characters. Audiences deserve a happy ending every now and then.

With Titanic and Avatar under his belt, Cameron could put his name behind a Howard the Duck remake and it’d instantly become one of Hollywood’s hottest properties. But if he’s going to back more empty spectacles like Sanctum, we’re in for some trouble. On a positive note, he’d be wise to give Grierson another shot; Sanctum shows that the Aussie filmmaker has the abilities necessary to stage effective action. Unfortunately for ticket-buying filmgoers, Grierson’s craft skills far outweigh his script concerns and eye for acting talent. That being the case, Sanctum is the pits.