Rory Glassen is selected to join an elite SAS cell. They are sent to Libya to seek retribution for the near-death torture of two of their SAS troopers, at the hands of a medieval-run empire led by a despotic Sultan. What was to be a milk-run operation turns sour, as a battle of wits to survive soon develops between two warring factions.

Sultan and Rory lock horns, trying to outwit each other and prevent any more deaths. It is only when a most unexpected ally emerges from Rory's distant past, and offers the cell information, that a solution appears. Like worms, they burrow into the catacombs of the old Roman Fort on which the Sultan's Palace is built and seek their revenge.