COLD, grey and uninviting, Gregory Hoblit's earnest Second World War PoW drama Hart's War still manages to pack an emotional punch. It just doesn't take any joy in doing so.

Privileged by birth and assigned a desk job, young Lieutenant Thomas Hart (Colin Farrell), a law student before the war, finds himself in a prisoner of war camp deep inside Germany.

His detached idealism about the nature of war already challenged, his conscience finds little respite as he deals with day-to-day life as a PoW.

When a fellow prisoner is murdered - seemingly by black airman Lt Lincoln Scott (Terrence Howard) - Hart is assigned as his defence attorney by the camp's senior US officer, Col William McNamara (Bruce Willis).

Once again, Hart must scrutinise everything he holds dear as McNamara seizes the opportunity to use the court martial as a smoke screen for a daring escape attempt.

The mood is as downbeat as the film's drab setting.

There's a detached coldness about the events it portrays that makes its exploration of human sacrifice and stoic heroism all the more telling for the removal of sentiment.

But somehow, Hart's War is a long way from the hard-hearted gem it could have been.

True, there is none of the arrogant tub-thumping that often accompanies such films - and it eschews vacuous action sequences in favour of word-heavy character development - but it lacks the spark to press home its advantage.

Willis mumbles his way through the picture, never entirely convincing as the weary senior officer.

Farrell fairs better as the idealistic Hart, adding shades of grey to his character's black and white world.

Howard makes the most of a couple of key speeches but the real plaudits go to the supporting cast including Linus Roache as Willis's second-in-command and Marcel Iures as camp commandant Col Visser.

Hart's War tries so hard to avoid the most vacuous stereotypes - and largely succeeds - that it is blind to the encroachment of other, lesser clichs. Shame.

Nick Churchill