There is a reason And Then There Were None is the #1 mystery novel of all time. It is bloody brilliant.
I had so much fun reading this book. Have you seen the movie Clue? I now know it's a blatant rip off of And Then There Were None, but I love that movie. If you love that movie, too, you really need to read And Then There Were None.
Basically ten folks are brought to an island and each one is picked off one by one. Who is the murderer? You won't know until the end, and you'll be thrown for a loop a time or two.
I can't think of a mystery I would recommend more than And Then There Were None. It was pure entertainment and expertly done.