The haunted house structure - unseen forces and trapped folk picked off in baroque ways - is transposed to a trench on the Western Front. This adds new ingredients to the mix, self-satisfied rats and rank mud. Moreover, when the bedraggled band of British soldiers (including Bell, Rhys and Serkis) stumbles upon it, the trench is full of mangled bodies which they take to be the remains of German soldiers. This scene highlights a problem: combine a conventional horror movie with 'the horrors of war', and it's hard for supernatural unpleasantness to hold its own against man-made evils. The setting is also limiting on a visual level, the action adrift in mile upon mile of muddy ditches. Writer/director Bassett makes the most of a tight budget with a few nasty surprises, but the film chiefly relies on an overworked smoke machine permanently set at 'spooky evil mist'.