A woman's hateful ex is murdered in Bermuda, in this mystery by the Edgar Award-winning author who wrote the Peter Duluth Mysteries as Patrick Quentin.   Patrick Quentin, best known for the Peter Duluth puzzle mysteries, also penned outstanding detective novels from the 1930s through the 1960s under other pseudonyms, including Q. Patrick and Jonathan Stagge. Anthony Boucher wrote: "Quentin is particularly noted for the enviable polish and grace which make him one of the leading American fabricants of the murderous comedy of manners; but this surface smoothness conceals intricate and meticulous plot construction as faultless as that of Agatha Christie."   After three years away, Kay Winyard must return to Bermuda to stop her young niece from wedding wealthy Ivor Drake. Her family sees the marriage as a boon to their sagging fortunes. But Kay knows his true nature from her own dalliance with the man. After she left him, he married another woman--whom he abused, tormented, and drove to suicide out of pure malice.   Before Kay can convince her family of the truth, Ivor ends up dead from suspicious causes. Apparently, Kay was not alone in her feelings toward the man. But just because the victim was despised doesn't mean the killer can simply get away with it . . .