Do some research about Graham Green in order to provide some context to the novel.
Here is a summary of the plot:
“Recently retired bank teller Henry Pulling is carried away from his settled lifestyle when his long-lost aunt comes to visit him on the day of his mother’s funeral. Eccentric and flamboyant, Aunt Augusta has never been a conventional person, and she seems to have decided that Henry needs to have the stuffing knocked out of him. This she does, first by taking him with her on a money-smuggling trip to Istanbul on the Orient Express, and later she talks him into accompanying her on a trip to South America to rescue the love of her life, Mr. Visconti, who has got himself into trouble with his criminal activities. Along the way we learn about her life, Henry learns to relax and have fun and he finds out some startling secrets about his parents and his aunt.”
Pay attention to the setting(s) and the characters (how they change..or not).