A Handful of Dust is funny, dark, horrendously cyncical, and has the most terrifying ending I could possibly imagine. I really loved it, but I had nightmares for days after reading it.
It's the story of a good, moral man whose wife cheats on him and he has to deal with the gossip and the fall out in proper British society. Then the novel moves to the African jungle where he goes to explore in an attempt to get away from his life for a while. In both places he is forced to deal with the irrationality of others.
As some may know, my greatest fear is being unable to rationally explain myself, either because (a) something prevents me from being able to speak clearly and plainly, or (b) even when I do speak plainly and clearly no one else believes or responds rationally to me. This was the problem with Kafka's The Trial, and it's also what makes the ending of A Handful of Dust so awful for me. I don't want to give away the ending, but let's just say that the irrational response from others means that he will be essentially tortured for the rest of his life. Of course, I think that's Waugh's point. Had he remained in England, he would have also been tortured for the rest of his life by the irrational society that decided to make him the villian for not more kindly accepting his wife's infidelity. Note that he accepted it rather kindly, just not kindly enough.

You clearly have read a lot on this subject...quite informative..thanks for posting.