Prague in the 1950s was a city of fear and spies and sooty fogs, Charles Laurence writes in the opening lines of The Social Agent. As the son of the No. 2 man at the British embassy in Prague, Mr. Laurence observed with wide eyes a great deal during the years his family lived there. And he had to guess at a good deal more. Written long after these troubling years, The Social Agent is at once a meticulous dissection of fact and memory and a lyrical evocation of a now vanished world. As Mr. Laurence bravely recalls the bitterness and heartbreak of his family's glittering though tragic years behind the Iron Curtain, his story turns into a most intriguing tale of espionage. At the center of the story is a man whose magnetism, sensuality, and romance were legendary in postwar Europe: Jiri Mucha, son of the famed artist Alphonse Mucha and a man for whom everything was possible, including deceit, surveillance, and manipulation in his role as a social agent.