Sparkling cyanide.

Six people sit down to a sumptuous meal at a table laid for seven. A sprig of rosemary -- 'rosemary for remembrance' -- marks the empty place. It is the first anniversary of the horrific death by cyanide-laced champagne of the beautiful and troublesome Rosemary Barton. The assembled guests are the same participants at the meal a year prior, and Rosemary's widower, George Barton, is determined to prove that one of them is a murderer. But George's dinner party, and his plans for justice, will go terribly awry, as another death will come to haunt this date. Colonel Race of the British Secret Service, friend of Hercule Poirot (and a featured player in Cards on the Table and Death on the Nile), is on the scene to investigate.