Claustrophobics are advised to steer clear of this deliciously high-concept drama, set entirely in the back of paddywagon. An introductory scroll reminds us of the context for this nail-biting political thriller. The year is 2013, just after the Egyptian military toppled the Muslim Brotherhood government of Mohamed Morsi. Army chief Abdel Fattah el-Sisi has seized power. Violent clashes between supporters and opponents of the then-elected Muslim Brotherhood government, are erupting all over Cairo.

The police respond with chaotic bluster, by throwing two journalists – Adam (Hany Adel) and his photographer Zein (Mohamed El Sebaey) – into the van. The detainees are soon joined by demonstrators celebrating Morsi’s ousting, and later, by pro-Brotherhood activists.

Tensions (understandably) rise in the 8m-squared space, often between those who are nominally on the same side. A nurse (Nelly Karim) is furious that her husband (Tarek Abdel Aziz) dragged their adolescent son (Ahmed Dash) along to the rally that has landed all three of them in custody. Brotherhood activists insist that they stand in groups that separate those who merely vote for the organisation from those who pay membership fees.

Outside, soaring temperatures, shootings, crazed crowds, and an absence of leadership and available prison cells, leave the overcrowded vehicle stranded, to bake in heat, uncertainly and fear.

A lone good cop, a conscript named Awad (Ahmed Abdel Hameed), takes pity when young Islam activist A’isha (Mai El Ghaity) desperately needs to relieve herself, but his efforts are not rewarded.

Mohamed Diab's eagerly awaited follow-up to Cairo 678, was shot largely in secret. Despite the film's careful inclusion of all possible political persuasions (and some apolitical persuasions: one detainee is more interested in handing out his DJ business cards than in the kerfuffle outside), and despite its' old-school 'Why can't we all just get along?' humanism, Clash has irritated Egypt's ruling class. Last year, a 10-minute segment on ERTU, the state-operated TV broadcaster, accused Diab of being a spy. Other outlets suggested that the filmmaker supported terrorism, the Muslim Brotherhood, and (huh?) Zionism.

Ignore the propaganda: this is a very fine picture, worthy to stand shoulder-to-shoulder with such tricky, similarly themed films as Lifeboat and Lebanon. Ratcheting tensions and genre thrills drag the viewer, like the unfortunate characters, into murky political turmoil.

Props to a committed cast, a brave director and to DOP Ahmed Gabr for reminding us that “cinematic” doesn’t have to mean wide, open spaces.