The title character is dead when the movie begins (a hit-and-run accident), and some time after her death James Coburn invites the assorted characters to his yacht to play a crime-solving game. At first it's hilarious and fun, but then bad things begin to happen and there's a real murder to work on. I'm not sure how it all hangs together, but if you've never seen it, it's a lot of fun just for the all-star cast. They seem to be enjoying themselves immensely, and maybe you will, too. It was written by Stephen Sondheim and Anthony Perkins, so that's a bonus for you.