February, 1917. A lone German agent is despatched to Washington to prevent the British delivering a telegram to President Woodrow Wilson – by any means possible. For this is the Zimmermann telegram: it contains a devastating piece of news which is sure to bring the USA into the war on the side of Britain and her allies.

Having fought in the trenches himself, Max Volkman knows that America’s involvement will only prolong the slaughter of innocents and is implacable in his determination to kill the British envoy carrying the telegram. But when his pursuit of the Englishman leads him to the home of American heiress Catherine Fitzgerald, wife to one of Washington’s most powerful politicians, he is presented with a terrible choice: loyalty to his comrades in the trenches or the loss of the one woman he has ever truly loved.

His decision will determine the outcome of the First World War.