Sandy and Dennys, twins and middle children in the Newbery-winning A Wrinkle in Time, are transported to the time just before the Flood. With a Finn grounding in Genesis, this is the kind of intricate tale with complex characters and relationships that L'Engle's readers have come to expect. Her ancient world of desert and oasis are stark in their simplicity, yet the evils precipitating the Flood mirror today's. Old customs are flouted; even Noah has quarreled with his father, and young women are wedding nephilim, biblical "giants in the earth," drawn here as fallen angels who change from man to beast at will. The boys, 15, become compassionate participants in preflood events, helping where they can (they reconcile Noah with his father) but always aware that they're "not supposed to change the story." Poignantly, they realize that the flood failed in the long term; human nature is the same. Noah was before Babel; L'Engle's universal "Old Language" is spare, direct, without colloquialisms. Her reiterated descriptions--baboons clapping at dawn, the brilliance of the singing stars--lend a mythic timelessness to the setting. A carefully wrought fable, entwining disparate elements from unicorns to particle physics, this will be enjoyed for its suspense and humor as well as its other levels of meaning.