The Comforters, Muriel Spark
The novelists of the 1930s developed narrative techniques based on the movies: short sharp scenes, characters differentiated by dialogue, dropping readers into the middle of the action, patterning scene changes to built plot suspense. The huge changes in technology in previous decades, such as radio and movies, were behind these innovations.
By the time Muriel Spark came along in the 1950s, technological innovation was running at a different pace. She uses the techniques developed by Waugh, Greene, Firbank, such as running dialogue for line after line without identifying the speaker, but her innovations are to do with perspective. Famously in The Prime of Miss Jean Brodie she uses flash forwards to create a cubist pattern in the plotting, building suspense by giving away the outcome.
The Comforters was Muriel Spark's first book, and is made up of hallucinations, elderly criminals, corrupt catholics, the naive Upper Middle classes, a possible ghoul, a car accident. Most importantly, Spark's main character knows she is a character in a novel, which she is unable to prove to anyone else. They assume she is mad, but she is the one who understands and parodies the sinister plots of some of the other characters. The whole book is a sort of elevated mystery novel that has the story of a thriller but the morals of a bildungsroman. Spark must have been an influence on Jane Gardam.
While she wrote this, Waugh wrote an autobiographical novella about his own hallucinations. It's a perfect example of the way fiction was moving on. Spark's book has all the techniques of Waugh but with her innovations of perspective.
The action moves fast, the jokes are good and the ending is neat and effective. If you are Catholic or know about Catholicism it's probably a more satisfying novel, or at least an easier novel to understand.