Well, this was a difficult book, but one we should all read, I think. The protagonist is a spy, or perhaps counter spy. He's two people in one, so to speak. The story is basically his written confession, comprising over 300 pages, to a "Commandant". So, mostly, we're guessing that he got captured by someone and is in a prison camp or re-education camp, or something. We do find out what it is by the end, but I'm not telling.
The action in the narrative takes place from 1975 to two or three years after. At first glance, the protagonist is the aide of a General in the Vietnamese army, that is the south Vietnamese army, ARVN. They are the folks the U.S. propped up to fight against the North Vietnamese, who were headed by Ho Chi Minh. Ho Chi Minh had essentially driven out the French colonizers in 1954 or thereabouts, but gained control of only half the country. He spent the following 20 years trying to unify the whole country. The unification would be under "Communist" control, which is to say, Ho Chi Minh was propped up by the Chinese Communists. In essence, Vietnam was a pawn in the Cold War.
Anyway, the protagonist is an aide for "the General", but in fact, he is an agent of the Communists, reporting the General's plans and doings back to them. His conduit is his old pal, Man. Back in High School, he, Man, and another friend, Bon, became blood brothers. They vowed to support and defend each other to the death. Well, it seems there's a problem, in that Bon became a loyal subject of the South Vietnamese. But that didn't affect their brotherly ties.
Anyway, we have the "fall of Vietnam", which was 30 April 1975. The army of the North were marching into the city. People fled as best they could, on planes, helicopters and so forth. The protagonist and Bon managed to snag a spot on the last airplane out of the Saigon airport (along with the General and his family and many others—hundreds of others?). They went to Guam, and eventually to the U.S.A., where they tried to build new lives. Man stayed behind to join up with his Communist comrades. He had had the protagonist flee so that he could keep tabs on the doings of the exiles, especially the General. The reports were to be directed through an "Aunt" who lived in Paris. Much of the reports were mundane and non-controversial. But hidden within the messages, in invisible ink, were the important facts.
They build lives for themselves in the U.S., but the General wants to develop a force of former ARVN veterans to invade Vietnam and take it back from the Communists.
Well, I could go on, but doing so might mean I'll never get done here and move on to other things. Suffice to say, this book gives some much-needed insight into our war follies from 50 years ago, which remain with us today, albeit in a different part of the world.