You will get some grasp of the bravery involved in bringing this Iranian film to cinemas when you hear that, accommodating those at danger from the state, the film-makers have left much of the end credits blank (hence the gaps at the top of this review). There are ironies within ironies there. The benign redaction comes at the end of a film that has terrible things to say about censorship in Iran. It concerns intellectuals who look and talk very much like their counterparts elsewhere in the world. They discuss their work in shady rooms. They (dangerously in that country) swill back the odd glass of vodka. But death and torture are always at their elbows.

Toying with our emotions in tricky fashion, Mohammad Rasoulof, a frequent, unwilling guest of his nation, focuses much of his attention on a pair of government hoods sent to deal with an errant writer. Morteza is an efficient killer who has squared away his conscience. Khosrow is an altogether more interesting figure: a divided man working to pay for his sick child's medical bills. Dostoevsky would have savoured the torments that Khosrow endures as he commits himself to his grubby task.

Astonishingly for a film made in Iran, the picture allows no such ambiguity about the state’s attitude to culture and freedom. This is an inherently evil system run by petty men of ruthless ambition. Of course, such monsters are a gift to the political thriller.

Rasoulof constructs a vivid portrait of a paranoid state, but he also manages to incorporate some fingernail-endangering tension into the piece. A singular film that demands further exposure.