Del-Del

This novel's unusual title befits its mad foray into the occult, science fiction and severe psychosis. 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. Kelleher ( Brother Night ) plots an unusual course for a sibling death theme, with confusing results. Beth's deft narration admits to the red herrings that confound the family (and pad the story): the theory, for example, that Del-Del is inhabiting Sam's body while on earth. The dialogue, dotted with expletives, slows the proceedings when Sam speaks in backwardly spelled English, and Grandma's heavy Polish dialect grows tedious. A pat resolution may annoy readers who have the persistence to reach the novel's end. Ages 12-up. (June)