At very best, this cheap horror is a run-of-the-mill British exploitation flick with nothing new to say; at worst, it's classist, deeply conservative and completely narrow-minded.

It is an expertly crafted thriller with a mastery of tension-building techniques.

Gritty and claustrophobic, this British horror-thriller holds our interest with well-played characters rather than the wobbly plotting.

A decent premise is let down by a terrible script, dour colour scheme and some shockingly bad acting (even the usually fantastic Sheridan Smith is a little clunky). Think Attack The Block without the humour, pathos, technical skill and well chosen soundtrack.

The biggest influence on the current crop of low budget film-makers, particularly those from Britain and France, seems to be John Carpenter. This should be a positive but what few of them realize is that it takes more than a synth score and a few bad-ass characters to emulate the thrills of his movies. "Tower Block" is a riff on "Assault on Precinct 13" but where Carpenter's film had a police station about to be shut down which found itself under siege from an L.A gang, here it's a London tower block which is on the verge of being demolished. The last remaining residents, conveniently for the plot, are those residing on the top floor. The film kicks off with a teenage boy beaten to death by two thugs in the hallway of the top floor. Smith tries to help but receives a beating for her troubles and when the police ask for witnesses she, along with the other residents, deny any knowledge to keep themselves safe. We then cut to three months later and the residents wake to find a sniper has them pinned down from an adjacent building. From here the limits of credibility are stretched. Somehow the sniper has found the time, in just a few hours, to rig the building with booby traps and, of course, knock out cell-phone coverage. The tenants come up with various plans to escape their predicament but never think of the more obvious ideas like writing a message on a bedsheet and hanging it from a window. They consistently talk about how nobody will ever find them as though they were on a remote island in the Pacific rather than in the middle of the largest city in Europe. Along the way we get several twists and turns resulting in an awkwardly handled final reveal of the sniper's identity. Like most British films, the movie's strongest point is it's performances. O'Connell is particularly enjoyable as a chav version of Precinct 13's Napoleon Wilson. The central idea had potential but it seems co-directors Nunn and Thompson lack the ingenuity to pull it off. If Carpenter's film is a smooth ride in an elevator, this is a tough slog up the stairs. Take the lift.