Les Blair's film about the H-block hunger-strikers of 1981 is a high-minded, meticulously respectful piece of work (comparable in some ways to Maeve Murphy's The Follower, a film about the women prisoners), which actually proposes a noticeably more complex, even sceptical view of the macho republican leadership.

Measured and serious in approach, H3 follows the blanket protest of IRA prisoners in Long Kesh, up to the moment when Bobby Sands triumphs at the Fermanagh by-election in absentia, and wins a devastating propaganda victory against the London Government that had sought to strip the prisoners of "political" status.

This film gives the impression of treading very, very carefully; it brings a kind of control and containment to its material and avoids anything potentially sensational or inflammatory.

Where another, looser type of movie might have roamed, Traffic-like, to the streets of Belfast, and to the lunch tables of Fleet Street and Westminster, this movie is set entirely within the prison precincts, where emotional tensions are more or less restricted to fraught but disciplined strategic debates within the blanket-men, and the (traditional) lone liberal warder despised by the other screws.

By the end, I had the feeling that this restraint, though understandable, had meant sacrificing perspective and cinematic and dramatic potential. But then hunger strikes, although arguably more effective than suicide bombings, are necessarily a slow and interior business.

Blair's movie captures some humane and startling images: a new prisoner is forced to sing The Undertones' My Perfect Cousin to give all the other inmates an idea of what's in the charts outside, and all the blanket-men assembled at Mass, long-haired, bearded, muscle-toned through fierce workouts in the cells, look like a Last Supper made up entirely of Jesuses.

· Showing tomorrow as part of the London Irish Film Festival. Box office: 020-7328 1000.