The Conspiracy Files delves into the final mystery of 9/11: a third tower at the World Trade Centre, which along with the Twin Towers, also collapsed that day. But this skyscraper was never hit by an aeroplane. Seven years on, the last official report on the World Trade Centre has finally been published. The 47-storey tower collapsed seven hours after the Twin Towers and it has become the subject of heated speculation and a host of conspiracy theories suggesting it was brought down by a controlled demolition. Official investigators concluded that fire caused the collapse of this third tower at the World Trade Centre. But that makes this the first and only skyscraper in the world to collapse because of fire. The Conspiracy Files explores the many unanswered questions to find out what really happened and why some people refuse to accept the official report and insist there was a sinister plot to destroy the building.