(15, 127mins) George Clooney, Matt Damon, Alexander Siddig, Amanda Peet, Max Minghella, Michelle Monaghan, Gina Gershon, Greta Scacchi. Directed by Stephen Gaghan

Stephen Gaghan, the Oscar-winning screenwriter of Traffic, steps behind the camera to direct this intricate ensemble piece about intelligence and terrorism in the oil industry.

Inspired very loosely by former CIA operative Robert Baer's memoir See No Evil: The True Story Of A Foot Soldier In The CIA's War On Terrorism, Syriana is an incredibly complex mosaic of corporate corruption and double-dealing with more than 70 speaking parts.

The film rewards patience: The opening 30 minutes are particularly dense and demand our complete attention to make sense of the overlapping storylines.

Personal intrigues collide as the narrative skips between the corridors of power in Washington, the oil fields of the Persian Gulf, the sun-baked streets of Tehran and the air-conditioned conference rooms of Geneva.

Gaghan posits no easy solutions: Many questions remain unanswered and there is no neat resolution to the bloodshed and government power-brokering. Dialogue crackles. "Corruption is our protection. Corruption keeps us safe and warm," rants Texas oilman Danny Dalton (Tim Blake Nelson) to lawyer Bennett Holiday.

Syriana abandons the constraints of conventional story arcs, offering us a tantalising glimpse at a much larger drama.