In 1942 Claude Dansey, deputy head of MI6, infiltrated Henri Dericourt, double agent extraordinaire, into the rival British wartime secret service, SOE. The ensuing trail of destruction and betrayal led to the loss of over four hundred British and French agents.

Recruited as the man SOE so desperately needed, Dericourt penetrated the heart of PROSPER, SOE's biggest network in France. At the same time he renewed contact with Karl Boemelburg, head of German counter-espionage in Paris. Every movement, code and dispatch from the British agents was made known to Boemelburg; Dericourt gave him everything. His treachery finally led to the disastrous fall of the PROSPER network, and to the arrest of nearly one thousand men and women, hundreds of whom died in concentration camps.

Was it patriotism that drove Dansey, or was the Dericourt plan merely part of the secret war between MI6 and SOE, a war in which Dansey held all the weapons? All the King's Men is the dramatic account on one of the most ruthless secret operations of the Second World War.