When her husband was the British ambassador to Italy, the author lived in the former Roman home of Princess Zinaida Volkonsky and became intrigued with her complex, extraordinary life. The strength of this biography, however, lies in the prodigious research Fairweather undertook, rather than in the writing, which is somewhat stilted. Zinaida (1789-1862) was born into an aristocratic Russian family and became a highly attractive, intelligent young woman with a beautiful singing voice and a voracious appetite for literature; the princess captivated Russian society. She also fell deeply in love with Tsar Alexander, whose many romantic conquests may have included his sister. Although no firm evidence exists, the correspondence between the tsar and Zinaida points to a sexual relationship, the first of many lengthy love affairs for the princess. To stem gossip, in 1911 she was married to Prince Nikita Volkonsky, whom Fairweather describes as ""weak and lazy."" After the birth of their son, the princess fell into a severe depression, a condition that afflicted her many times during her life. The princess recovered, traveled widely, hosted famed musical and literary salons in Moscow, Paris and Rome and published several books of poetry and prose. Existing as she did at the center of European intellectual and cultural life, Zinaida became acquainted with many notable individuals, including Pushkin and Gogol, and Fairweather is particularly adept at weaving the major events of the 19th century into her narrative. Later in life, Zinaida settled in Rome, converted to Catholicism (becoming an almost fanatic devotee) and eschewed her privileged lifestyle by dedicating the last years of her life to serving the poor. B&w illus. (Feb.) Forecast: Though fascinating, the Princess Zinaida's life might seem too obscure to have a broad appeal. However, the British publication of the book early in 2000 was the occasion of a full-page story in Time magazine; it's possible that with review attention, a fair number of readers will be captivated by her unorthodox life.