THE CHAMBER: DIVING DEEP INTO BEN PARKER'S DEBUT

Mats is the Swedish pilot of a small submersible being rented out for research and oil exploration in the China Sea. When his craft, the Aurora, is commandeered by a trio of American special forces types, he goes along with the mission, trusting his British captain's word that nothing will happen. But Mats has worries. His craft is designed for two people, not four. It's old and temperamental. And they are right on the edge of North Korea's territorial waters. What could go wrong?

Of course something does go seriously wrong, and the four find themselves upside down in the damaged Aurora, stuck on the ocean bottom, with little power and the boat now a chamber filling up with water. And when contact is lost with the surface, with the likelihood North Koreans have boarded it, the odds increase against survival.

The Chamber is a title which suggests a horror movie, and first-time feature director Ben Parker's previous film was a horror short, Shifter. Indeed the film received its premiere at Fright Fest last year. But this is really a suspense thriller which plays out like a claustrophobic encounter session, the dynamic between the four victims shifting with each attempt to find a solution that might save their lives. Parker's control of the pacing is immaculate, the character shifts not forced, and if once or twice shocks are predictable, well, there is only so much you can do in that small space. It's a well-made work: Benjamin Pritchard's photography explores every inch of the space and every change of emotion, and Will Gilbey's editing makes the most of it. There's also a good score by James Dean Bradfield, of Manic Street Preachers, in his film debut. The Chamber moves without respite, while not overpowering the characters, which is what a good thriller should do.

It also works because of the cast. Johannes Kuhnke (best-known for Force Majeure) as Mats ('not Matt') has the same sort of Scandinavian calm as Ólafur Darri Ólafsson offered in Trapped. Which makes a nice contrast with the three Americans, Elliott Levey as the more practical technician, James McArdle as the hard man, and Charlotte Salt (who stole some scenes as Marguerite in Musketeers) as Red, the mission leader. McArdle is the only one of this British cast who doesn't quite convince as an American, but it is Salt who dominates the action in what is a striking performance; the one whose very American single-minded devotion to duty and to proving herself has to be overcome by Kuhnke's Swedish practicality. Or at least met halfway.

There is an an element of political thriller here, but it never really takes off, because of the relentless momentum of the action. It's not just the presence of the North Koreans, but more in the way Red's tunnel vision rebounds on them all, her willingness to lie and conceal, and her ultimate faith in her larger purpose contrasts with Mats' Swedish neutrality or humanity. It's left in inference only, but it's almost unmistakeable, especially because the tight setting and interplay of those two with the other two bring it into focus almost naturally.

This is an assured performance by all concerned, and its ending is something of a surprise, as well as making a conclusion that reminds you this four-hander offers elements of existential theatre as well as ocean-floor thriller. Ben Parker and his stars are three to watch.

The Chamber

written and directed by Ben Parker

starring Johannes Kuhnke, Charlotte Salt

released 10 March, available on DVD and download 20 March