Vita Sackville-West, novelist, poet, and biographer, is best known as the friend of Virginia Woolf, who transformed her into an androgynous time-traveler in Orlando. The story of Sackville-West's marriage to Harold Nicolson is one of intrigue and bewilderment. In Portrait of a Marriage, their son Nigel combines his mother's memoir with his own explanations and what he learned from their many letters. Even during her various love affairs...