Using the symbolic motif of flying as she did in Tar Beach (Crown, 1991), Ringgold reintroduces Cassie and Be Be Lightfoot, who soar above oceans that look like cups of tea and meet a ``ramshackled train in the sky'' whose conductor is Harriet Tubman. Aunt Harriet, as she is called, explains that the railroad in the sky retraces her route to freedom every 100 years. Meanwhile, Be Be jumps on board. Cassie, who misses the train, must follow, living the slave existence, always one step behind, hoping to rejoin her brother in Canada. What follows is a compelling journey in which the author masterfully integrates fantasy and historical fact in such a way that readers join Cassie in experiencing the fear and the mystery of such a trip. The spare but eloquent text conveys much information, and the artist's flat, primitive illustrations in acrylic on canvas paper lend power and symbolism to one of the most dramatic chapters in American history. Everywhere, Cassie finds clues leading her to Be Be. Everywhere, she receives whispered directions from Aunt Harriet that lead her forward. Everywhere, the threat of capture lurks in the background in the form of the sinister chalkwhite faces of bounty hunters. Although adults may have difficulty with literal interpretation, children with only basic background will recognize that the story is both fact and fantasy--history and allegory. With gripping immediacy, Ringgold puts readers in the story on the side of the victims, insuring, through powerful words and images, ``that we will never forget the cost of freedom.'' Groundbreaking! --Kate McClelland, Perrot Memorial Library, Greenwich, CT Copyright 1992 Reed Business Information, Inc.