The good doctor, the son of an assassinated Central American dictator, is coerced into working for a politician who is planning the next coup. Whether he knows it or not, he is a spy for the French government and others who have vested interests in his birth country. What it lacks in the spy category it more than makes up for in political intrigue. Along the way the doctor discovers who really had his father killed. As good as it gets until you graduate to John Le Carre.
One of the author's later books (1974). As in most of his stories, the plot sneaks up on the reader in the midst of apparent side tracks in the characters' activities. Of the British adventure thriller writers, Ambler is perhaps the writer most enjoyable to read, with the best-presented stories. I've read many of them and so far recommend them all.