Set on a rich American couple's island refuge in the Caribbean, this fury of a novel, charged with ideas, whips up a storm. Into the paradise comes first Jadine, the white couple's Sorbonne-educated protegee who is also the black serving couple's niece, and then an intruder -- angry, impoverished and black -- who calls himself Son. Morrison never flinches (although her readers may), and her book is menacing, beautiful and dense with undergrowth.  (CRB150, $13.95)