The quaint seaside town is the hiding place for the two most dangerous spies the Germans have working on their side. The crux of the matter is that these spies are most likely English and the English officials on all levels of the government who are sympathetic to the Nazi cause make investigation impossible. Intelligence brings in two perfect outsiders, Tommy and Tuppence, and tasks them with discovering who these spies are while working undercover. They are former intelligence agents who are not quite ready to retire and behind their positively ordinary appearance they are the perfect people to take down England's main threat.
I laughed at the loving condescension of the middle-aged sleuths' children for their parents. They think they're so important in their jobs and don't even suspect that their parents do more than knit and play golf to occupy their time. I admired the wits and the guts of the two patriots ready to sacrifice themselves for their country. I marveled at the dedication they displayed to each other, the affection and the partnership in everything their relationship is based on. I suspected everyone and in the end the bad guys were those I didn't even think to suspect. Hope you do better :)