July 1940: A month after the evacuation of the defeated and battered Allied forces from Dunkirk, a German invasion of England threatens. In this thrilling historical "what-if," Prime Minister Winston Churchill has resigned without naming a successor and leaders of Parliament are calling for an armistice with Hitler. Meanwhile, the Deputy Director of Counter-Espionage at MI5, Adam Strachan, faces his own daunting task. During a botched burglary, the fugitive Billy Houston commits murder and discovers his victim was in possession of Britain's plans to thwart the German invasion. No patriot, Houston is determined to get the information to the right people and help bring about a Nazi-run Britain. Strachan soon finds himself pursuing Houston through England, from London's blacked-out streets and seedy narrow lanes to the thinly guarded Channel coast and the Isle of Wight, in a desperate bid to stop the missing defense plans from falling into German hands. The clock is ticking, and Britain's immediate future is anything but secure.