And Then There Were None is one of Christie's most famous novels. It's not really a spoiler to tell you what's right on the back cover: Ten people are on an island and are murdered one by one. But there is no 11th person. How is it done?
There are two film versions, one made in 1945 and the other 20 years later with the title Ten Little Indians. I saw the 1965 movie version when I was a child, but luckily I'd forgotten the identity of the culprit. I did remember a key point to the plot, but that did not diminish my enjoyment of the mystery. Christie writes an engaging story with fascinating characters that keeps you hooked to the end.
Note: this was not as cozy a story as Miss Marple's The Murder at the Vicarage since there was a lot more hysteria and swearing. Still, it was a satisfying, quick read.