Mother Night is a novel which Kurt Vonnegut copyrighted in 1961. I guess he wrote it no later than that year. It's about a man named Howard W. Campbell, Jr., an American citizen, Nazi propagandist, and war criminal. I don't know if Campbell's name is deliberately meant to remind us of the famous crypto-fascist1 SF editor John W. Campbell, Jr., but Vonnegut spent enough time trying to be an SF writer that he must surely have been aware of the man.
Before the war, Campbell is a successful and apolitical German-language playwright in Berlin, married to a German actress. With the coming of the war, he is approached by an American agent who he calls his "Blue Fairy Godmother". This agent persuades him to use his social connections to spy on the Nazis, and to become an English-language radio propagandist much like Lord Haw-Haw or Tokyo Rose2. What he's really doing, of course, is getting coded messages out to the Allies, embedded in his propaganda pieces. Or so he claims. The American agent tells him that the US government will "deny all knowledge" etc., and that's just what they do.
After the war, Campbell ends up living in a cold water flat in Greenwich Village. His wife, to whom he was devoted above all else, died in the war. He has no further interest in living and continues to put one foot in front of the other merely by habit. He is found and identified by Vonnegutianly clownish neo-Nazis who admire him. They print a little article about him in their newsletter, and the jig is up. He ends up on trial in Israel, where he writes his memoirs (Mother Night itself) and chats with a guard who had also been a mole during the war: The guard had served in the SS, merrily undermining and betraying competent officers (competent at being pretty much evil, remember) while letting the idiots wax fat in peace.
At the last moment, Campbell's Blue Fairy Godmother comes forward and offers to testify on his behalf. Campbell looks over his options and turns him down. His life has been over for fifteen years. Execution as a war criminal seems less burdensome than to continue living as nothing at all.
All of Vonnegut's books are desolate and sad. This one is at a sweet spot in his journey from lousy-conventional-novelist to Vonnegut-plays-Vonnegut-as-self-parody. It's just Vonnegutty enough to work with Vonnegut writing it, and he's got enough real material to play with that he makes a real novel of it. Fifteen years later, he would have wrecked it with self-indulgence.
In 1996, Mother Night was "made into a movie", starring Nick Nolte in what I suspect was a catastrophic casting error. Nick Nolte?! Sam Sheppard would've been much better (if he's still acting), or even Ed Harris. Or so I assume. I haven't seen the movie.
1 Well, some people think so.
2 Ms. Rose, by the way, was a Japanese-American college student who happened to be visiting relatives at the outbreak of hostilities; she agreed to be a radio propagandist because it beat assembling bombs for a living. She was more or less apolitical, too. I got this information from John Toland's The Rising Sun: The Decline and Fall of the Japanese Empire.