Sassy socialite Kate (winniningly played with personable spunk by Franke Potente) gets locked in a subway station after she dozes off while waiting for the train. Unfortunately, a lethal and ferocious subhuman mutant beast named Craig (a genuinely scary portrayal by Sean Harris) is also in said subway station with Kate. Will Kate be able to survive the night? Writer/director Christopher Smith adroitly builds and sustains a substantial amount of nerve-wracking claustrophobic suspense, makes inspired use of the dark, dank, and dingy subterranean setting, relates the gripping story at a constant brisk pace, and delivers a sizable smattering of grisly gore. Better still, there's no silly humor to detract from the grim severity and stark intensity of the often gut-wrenching horror (a sequence with Craig brutally operating on a bound and helpless young lady is especially brutal and upsetting). Craig makes for a truly frightening and grotesque creature whose exact origins are never completely explained, although it's suggested that he's the toxic product of some kind of secret sadistic medical experiments (thereby making Craig at least semi-pitiable and hence as much of a victim as the people he stalks and kills). Potente scores strongly as a tough and appealing heroine; she receives sturdy support from Vars Blackwood as likable and sarcastic sewer worker George, Paul Rattray as twitchy heroin addict Jimmy, and Jeremy Sheffeild as coke-snorting would-be rapist jerk Guy. Danny Cohen's slick and agile cinematography offers plenty of striking spooky images while the shivery soundtrack by the Insects hits the spine-tingling spot. Well worth seeing.