Alice Keppel, the married lover of Queen Victoria's eldest son and great-grandmother to Camilla Parker-Bowles, was a key figure in Edwardian society. Hers was the acceptable face of adultery. Discretion was her hallmark. It was her art to be the king's mistress and yet to laud the Royal Family and the institution of marriage. Formidable and manipulative, her attentions to the king brought her wealth, power, and status. Her daughter Violet Trefusis had a long tempestuous affair with the author and aristocrat Vita Sackville-West, during which Vita left her husband and two sons to travel...