It's June 1941. Paul Duggan, a young Irish military intelligence officer, is on a secret mission to Portugal to uncover German intentions towards neutral Ireland and, even more secretly, to find out who had informed the Americans of an Irish Minister's undiplomatic comments while in Lisbon on his way to Washington to plead for arms.

Meanwhile, an unmarked American plane crashes in Ireland and its cargo of beer, cigarettes and caviare make their way into the local black market with unforeseen consequences. Then it turns out there was something more than booze on board - a piece of secret military hardware of great interest to the Germans.

Duggan and his colleagues find themselves in a complex game of diplomacy and disinformation as politicians in Ireland and America fall out and the spy agencies of Germany, Britain and the United States maneuver for political and military advantage. With the help of his Special Branch friend, Peter Gifford, he tries to unravel the plots and avoid the pitfalls. To do so he has to return to Lisbon, the war's spy center, where the interlocking intrigues threaten the future of Ireland's relations with America, put its neutrality at risk, and finally threaten his own life and that of the woman he loves.