Tobruk, Libya 1941.

Surrounded by German and Italian armies like 'rats in a trap,' the British forces in Tobruk knew that they could not let the vital deep-water harbour in eastern Libya fall. Should the Germans claim the city, they would gain unlimited access to the oil fields of the Middle East and destroy Britain's hope of defeating the Nazis.

Naming themselves the 'rats of Tobruk,' the British soldiers had held off the advance for eighteen months when, on 15 June 1942, fresh Allied troops were sent to reinforce their ranks. Amongst these new troops was young, cheerful Theodore 'Issy' Schurch. Just five days later, the Germans attacked the weakest point in the British line and infiltrated the city. 32,000 Allied soldiers were captured, along with vital military equipment, and the surrender marked the British Army's second biggest capitulation in the War.

Suspicion about a mole within the British army's ranks immediately spread, and history went on to blame South African commander Klopper for surrendering without firing a shot. No one thought to question the popular, 'brave' Issy Schurch.

This is the story of one of the greatest betrayals in Britain's military history and of a hunt for justice - for the ultimate 'desert rat' - that confounded MI5, MI6 and MI9 alike.