In 1990s Khartoum, MI6 officer Haydon Talbot uncovers a rising extremist threat as Al Qaeda plots a major attack on London. With sceptical superiors and his career at risk, he races to stop the bombers before it's too late. In the aftermath of the Soviet defeat in Afghanistan, Haydon Talbot is posted as MI6 Station Chief Khartoum, tasked with monitoring the mujahadeen fighters who have flocked to Sudan, welcomed by the radical Islamic regime. His CIA counterpart, Pete Monkton, introduces him to the Sheikh, a Saudi financier who worked alongside Monkton in Peshawar, and now claims to be a horse breeder.

Monkton plans to use the Sheikh's Afghan-Arab connections to attack Imad Mughniyeh of Hezbollah, a priority target of the Agency. Haydon becomes convinced that Khartoum is becoming a crucible for dangerous extremist groups, and after terrorists attack a MI6-owned hotel, killing one of Haydon's agents, he learns that The Sheikh and his nascent group, Al Qaeda, are planning a major bombing operation in London. Unable to convince his sceptical bosses of the imminent danger, Haydon puts his career on the line in an attempt to thwart the bombers.