Critical Zone

With his debut Kami's Party, Ali Ahmadzadeh offered a day in the life of a group of middle-class Iranians, largely from within the confines of a car. Now his latest film takes us on a character study odyssey through the night streets of Tehran as we go along for the ride with drug dealer Mr Amir (Amir Pousti, a non-professional, like all those involved, although you wouldn't know it). His shaggy beard and hair recall the iconographic look of Christ and, in a way, he is ministering to the "sinners" and the lost souls of the city.

A muscular silent opening shows drugs and Amir moving through the brightly lit road tunnels of Tehran before taking us to Amir's apartment, where his bulldog Mr Fred is his lone companion. We watch as Amir prepares not just bags of drugs but also bakes hash cakes - just one of the many reasons this film has already fallen foul of the Iranian authorities who pressured the director and his co-producer Sina Ataeian Dena to withdraw the film from Locarno before its world premiere. Neither that nor the travel ban dished out to Ahmadzadeh stood in the way of the film taking home the top prize Golden Leopard at the festival at the weekend.

Once Amir is back behind the wheel, the ever-present voice of his female sat nav calmly instructs him to take a left here and a right there. Ahmadzadeh has never been one to shy away from a large metaphor - his first film involved the dead body of a man whose name translated as "Hope" being carted about in the boot of a car. Things are a bit more subtle here but there's a deep irony in Amir being constantly told what to do by the quasi-authority figure of the sat nav while offering up a means of escape to the city's youth that doesn't rely on roads to take them there. Elsewhere, a staircase becomes an Escher experience, again emphasising people travelling without reaching an endpoint.

The writer/director isn't afraid of stylistic flourishes in general - with the trippy surreality of parts of the film fitting with its drug-dispensing lead. The fact the film was shot using clandestine cameras and without the permission of the authorities, meanwhile, adds to Critical Zone's sense of edginess. At one point the camera spins about within the car as though enduring its own bad trip, while the sound design throughout emphasises noises off screen as well as amping up the mood at key moments. Among the encounters is an addict desperate for a shoulder to cry on and an air stewardess drug mule, whose act of defiance is like a cri du coeur. There's humour here and melancholy. Most of all, however, there's a pointed air of defiance from a younger generation that refuses to be cowed.