What a great novel! This is a classic British mystery that kept my engaged and intrigued. While it is 11th in a series, I have never read any of the others and I didn't feel I missed a thing by starting with this one. It's definitely a stand-alone mystery.
A British novelist, Adrian Messenger, shows up with a list of seemingly unrelated people and wants his friend, who is in law enforcement, to check them out. Just find out if they are still alive or not. That's all he wants to know. When Messenger is subsequently killed in a questionable airplane accident, the search begins to find out if the list is related to his death and how the people on it are related to each other. The answer will take them into the upper echelons of British aristocracy.
While easy to read, the book does assume the readers are smart and clever. I like a book that assumes I'm intelligent. It's a smart, classic mystery writing at it's best!