The story of Fidel Castro's illegitimate family, this chronicle -- by a journalist who logged hours of interviews with her subjects and had access to many personal documents -- is in many ways a tale of Cuba's multiple transformations during the 20th century. At the book's center is Castro's former mistress, Naty Revuelta Clews, a bourgeoise of European stock who bore Castro a daughter. Included are many of Castro's love letters. (Not every book can boast that.)  (CBA26, $15.00)