Satirist Chris Morris has pulled off a remarkable feat with Four Lions, managing to undermine and belittle Muslim suicide bombers without criticising the religion that their misguided fanaticist zeal is based upon. Along the way he also finds time to poke fun at inept police officers, who Menezes-like shoot and kill the wrong man (twice).

Four Lions has laugh-out loud gags interspersed with moments of real reflection. Why shouldn’t we find these dumb wannabe martyrs funny? At its core, this is a traditional buddy movie, but Morris – whose media career started at BBC Radio Bristol before The Day Today and Brass Eye, and is the brother of Bristol Old Vic artistic director Tom Morris - never lets us quite forget the consequences of what these five Yorkshire friends are planning.

The friends are led by Omar, played by the excellent young actor Riz Ahmed. Their aim is to become martyrs and to this end they go on a terrorist training camp to Pakistan, with the final goal to cause death and destruction at the London Marathon disguised in animal costumes.

Omar is the only fully-formed member of the group, which is a shame because the others become cartoon-like caricatures. That, however, is this film’s only criticism.

Omar – clearly based on the London 7/7 bomber Mohammad Sidique Khan – is shown to be a family man with a young wife and child, so it is a shock when he goes about organising his and his cohorts’ death so level-headedly.

When suicide bombers do not succeed in the real world, their attempts at martyrdom can seem tragically comic - see for example the botched attempt to drive into Glasgow Airport and burning up inside your crashed car, or prematurely detonating your bomb in the toilets of a restaurant burning your face and hand – so Morris and his fellow writers, Sam Bain and Jesse Armstrong from Peep Show and In The Loop fame, have tapped into great comic potential.

Four Lions is a comedy about a deadly serious subject. Like the five would-be martyrs, it doesn’t hit all its targets successfully, but it is nonetheless a brave and excellent film.

Four Lions is showing now at the Watershed. More info here.