In December, 1941 the Blitz is at its height. London is shuddering under the relentless assault of German bombs. Across the Atlantic, Roosevelt seems determined to keep the US out of the war. Tom Wall, an American soldier wounded while fighting with the Allies in Crete, wakes up in a London hospital. Physically weakened and suffering from combat fatigue, Tom is aware only of a burning need to find his brother, a diplomat also in London. But British Intelligence has other ideas. They want Wall to help secure a national asset - the Double Cross System, an intelligence operation now at risk from a German masterspy. Amid the bombsites and blood-stained alleys of blacked-out London, Tom pursues a quest, whose goals are constantly shifting, in pursuit of an enemy whose identity is ever changing. Meanwhile a Japanese war fleet is steaming towards Pearl Harbor ...