Sparkling Cyanide - Agatha Christie

A beautiful heiress is fatally poisoned in a West End restaurant...Six people sit down to dinner at a table laid for seven. In front of the empty place is a sprig of rosemary - in solemn memory of Rosemary Barton who died at the same table exactly one year previously.No one present on that fateful night would ever forget the woman's face, contorted beyond recognition - or what they remembered about her astonishing life.