I've never really warmed to this story very much, but I always enjoy reading any story in which Mrs Oliver appears. This novel has some very funny scenes with her. There is also amusing moments when Poirot is depressed at being told he is "too old" (see below).Nevertheless, I find the story a bit depressing; in fact, I find many of Agatha Christie's later stories very depressing (the one written after this, "Endless Night" is the most depressing of all her novels).Norma Restarick is a "third girl" - I've not heard that phrase in the United States, and I'm not sure how common it is in Great Britain. It is explained that when a young woman takes a flat, she often has a friend to share it and help with the expenses. If there is room and they need additional help, they advertise for a "third girl" to help with the expenses... this is often someone that neither of the other two know (or may know slightly).Norma goes to see Poirot, stating that she "may have committed a murder", which piques Poirot's curiosity: you'd think anyone would know whether or not one murdered another. But after meeting Poirot, she decides that he is "too old" to help her, which depresses him.Despite her giving up on him, Poirot does help her and involves his friend, Mrs Oliver.As is usual in Agatha Christie's mysteries, there is plenty of misdirection and it's hard to determine who is guilty.It is well worth reading it if you haven't read it; it just wouldn't be my first choice of a Poirot novel.