Guards line up guests against the wall, shining torches in faces and barking commands and questions in Russian. But if such a welcome seems disorientating, no one’s seen anything yet.

Played out across four floors, a ground level sewer and a tunnel system of  a massive warehouse near Barbican, this version of Secret Cinema challenges its participants to piece together a series of clues to guess the film, set in post-Second World War Vienna.

Locations include an empty apartment with a bewildered landlady; a children’s hospital that looks as if has beentransported in from Chernobyl; a swanky cocktail bar, compete with gambling; a secret laboratory; a police station; and many more tiny rooms offering a tease of what the movie may be.

Because almost everyone has donned some form of costume, there’s no telling who’s really a guest and who’s a Secret Cinema actor, meaning the more participants get involved, the more they find out. Even then, it’s always the people least suspected that will offer the surprises to keep guests on your toes.

Imagine being coerced into giving information by a heavily accented Austrian policeman; being fed black market liquor by a street hustler; and coming face to face with a scientist brewing illegal penicillin. London, for an evening, seems another word away.

The secret, it turns out, is The Third Man, the 1949 film noir, the screenplay for which was written by Graham Green.

Directed by Carol Reed and starring Jospeh Cotton and Orson Welles, it’s long been considered a masterpiece, but is not the only one encountered during the evening: the entire production is an extraordinarily well-run work of entertainment genius. In fact, the only disappointment of evening comes when the final credits appear on screen, meaning Vienna vanishes and London returns.

Unfortunately, the The Third Man run has finished at Secret Cinema – 19,000 participated – but another experience will start up soon.

Keep your eyes peeled at secretcinema.org or Facebook for the next one. This exciting, truly unique event is one you do not want to miss.

WORDS: JAHN VANNISSELROY