Sparkling Cyanide +CD (Agatha Christie Readers)

Six people sit down for dinner at a table laid for seven. No one can forget the night exactly a year ago that Rosemary Barton died at this same table surrounded by the same people, her beautiful face turned blue with cyanide poison. Rosemary had always been memorable and people had strong reactions to her. Did one of the six people at dinner feel strongly enough about her to kill her?