Winston Churchill is dismayed to receive unauthorised information on the perilous state of Britain's rearmament programme in the year 1937. The Foreign Office brings in Lord Edward Corinth to investigate the leaks. Falling rapidly under Churchill's spell, he is sidetracked from the investigation to concentrate instead on finding the murderer of a Foreign Office official, who could have been one of Churchill's sources. He soon finds himself trying to untangle a web of deception that threatens the security of the state.
Following a second murder within the FO, Edward sets out for Spain to find the murdered mans son. Once there, his real objective though is the need to satisfy his gnawing fear that his friend Verity Browne is in extreme danger. Reporting on the Civil War for the New Gazette, Verity scents a scoop when she is given secret information that the enemy is planning an attack on the undefended town of Guernica. With Edward in tow, she arrives just in time to witness a barbarous aerial bombardment on a civilian population with no means of defending itself.