Dau is not so much a film as a document of a mass human experiment. The result is dark, brilliant and profoundly disturbing.

For three years up to 400 people, only one a professional actor, lived for months at a time on a city-sized set specially built for the shoot near Kharkov, Ukraine. Modelled on the real Kharkov Institute of Experimental Physics between 1938 and 1968, every detail on the set was scrupulously in period, from the light fittings to the lavatory paper. The participants — who included a real-life Nobel Prize winner and famous orchestra conductor as well as real former KGB and prison officers — were required to live in role 24 hours a day, eating Soviet food, wearing Soviet underwear and undergoing Soviet-style total surveillance. Hidden microphones were in every room, and the installation was supervised by its own secret police.

In essence, director Ilya Krzhanovsky created a vast Stanford prison experiment — but instead of lasting just five days and involving 24 subjects like the 1971 original, Dau involved hundreds of volunteers over months. Camera crews roamed over the set day and night, filming semi-scripted exchanges as the participants philosophise, interrogate one another, argue, get drunk, fight, fall in love and have sex. And like the participants of the Stanford experiment, the inmates of Dau began to inhabit their roles to a terrifying degree.

The result is 13 interwoven feature films, each following the storyline of different members of the Institute’s community. The central figure is modelled on its real-life director, Nobel-Prize winning nuclear physicist Lev Landau — hence the title — who was not only one of the fathers of the Soviet atom bomb but also a proponent of free love with an interest in esoteric spirituality. Other storylines follow a canteen waitress who falls foul of the KGB; Landau himself (played by celebrated Greek conductor Teodor Currentzis) bringing an old flame to the institute while his wife is away; and a pair of janitors who embark on a torrid homosexual affair. The odd international celebrity appears — Marina Abramovic, Willem Dafoe — and the music is by Brian Eno.

The films themselves are an almost indescribable mixture of devised acting, Big Brother eavesdropping and cinéma vérité. It’s a totally original and striking aesthetic — though often its languor makes it close to unwatchable. Many key scenes are simply played out in real time with no retakes, the only cuts being between two cameras observing the same action. When that action is two characters reminiscing whimsically about their lost love (in Greek, to boot), the result is both uncomfortably intimate and frankly tedious. A group of janitors — actual real-life cleaners, recruited by Krzhanovsky’s team — spend an hour getting loudly drunk and talking about nothing in particular. We follow a couple of them to their dormitory, where they first beat each other up and then begin making violent love. The 40-minute scene, filmed in a single take, is by turns moving, revolting, violent and extraordinarily pornographic. Punches to the face, vomiting and sex are unsimulated. In another of the films, an actual former prison director playing a KGB interrogator sexually assaults a female prisoner with a bottle. A group of scientists is depicted doing experiments on infants with Down’s syndrome (though none were harmed in any way, Krzhanovsky insists).

There were moments during the filming of Dau when the experiment spiralled out of control. One Moscow museum director recounts that her son — one of the volunteer actors — was arrested on the set and imprisoned in horribly authentic Stalinist conditions in Dau’s in-house jail. Frantic calls to Krzhanovsky failed to get him immediately released. The actual former prison guards playing prison guards ‘have their own rules’ was the explanation. Several actors have reported suffering from post-traumatic stress after their experiences at the Institute.

Dau isn’t the first film where the director has imposed collective stress on his cast in order to push for maximum verisimilitude. Martin Sheen suffered a heart attack and nervous breakdown while filming Apocalypse Now, while Dennis Hopper was in a state of near-permanent drug intoxication and Francis Ford Coppola himself suffered a seizure. But in Dau the psychological manipulation and the menace has a very specific structure and intention — to recreate accurately a repressive society underpinned by total surveillance and the constant threat of violent arrest. Dau’s wider theme is that modern Russia continues to be a kind of mass human experiment where the state manipulates and controls its citizens — albeit in less brutal ways than the Soviet Union.

The scale and ambition of Dau are so breathtaking that they border on the surreal. For the première Krzhanovsky has hired not one but two theatres in central Paris — the Théâtre de la Ville and the Théâtre du Châtelet — in addition to space in the Centre Pompidou and has decorated the whole of the upper floors and administrative offices in authentic 1950s Soviet style. There are kitchens and studies, dormitories and laboratories inhabited by actors who read, cook, make dumplings or just sit staring vacantly into space, as oblivious to visitors as actors in a Punchdrunk performance. Some spaces lurch into the bizarre — the grey paint of the lower part of a wall also covers a polar-bear skin and the bottom half of framed photographs. One room, inexplicably, is full of vintage West German sex toys. Throughout the various spaces, microphones on the walls hiss menacingly. A lecture series by international experts on everything from shamanism to string theory, begun on set in Kharkov, continues in Paris. A nearby restaurant has been taken over and completely redone as a Soviet cafeteria, serving authentically terrible Russian station food such as boiled sausages and cabbage soup.

And the experiment continues on the visitors themselves. Every applicant for a ticket — known as a visa — must fill in a lengthy psychological questionnaire in order to receive a personally appropriate selection of Dau films. After watching, visitors are invited to enter screened-off booths in order to discuss their experiences with various ‘spiritual professionals’, including rabbis, priests and shamans (I got a shaman, though disappointingly a French one in mufti.)

This entire mad ten-year project has been financed by Sergei Adoniev, a Russian telecoms oligarch who has also funded theatres, documentary film projects and a design university in Moscow. The budget is a closely kept secret, but it’s rumoured to be well over $100 million. The editing alone took six years, and was done at 100 Piccadilly in London, the building leased in its entirety by the production company and transformed into a ‘fifties Dau space, complete with a 24-hour Soviet cafeteria’. The launch was due to be in Berlin, where Krzhanovsky wanted to rebuild, then destroy, a section of the Berlin wall. The city authorities refused. Dau’s next stop will be in Berlin — minus wall — and then London. It’s the strangest, and most unsettling, piece of art to come out of Russia in years.