'Beth, 18, looks back on the events of the past four years, beginning with the anniversary of her sister's death from leukemia. Sam, a stoic seven-year-old genius, suddenly changes from a docile brother to an uncontrollable child he calls Del-Del (from the constellation Delphinus). Convinced that the boy is possessed by the devil, his distraught family consults an exorcist, whose work temporarily mitigates the ravings. But it is Beth who ultimately risks her life to uncover the psychological foundation of Del-Del's genesis.'
Source: Publishers Weekly.