David Stark is twelve, living in California near Los Angeles, a child of divorce. His sister Lizzie is very bratty; his mother is ill with an unspecified disease, rapidly losing weight--and wittily beleaguered. (""As of today, you kids make all the decisions. I'll just go to work and come home and do whatever you say. For every day you get older I'll get a day younger, and before you know it we'll be right back here again with me asking you if I can skip work for a day. How would that be?"") But then stepsister Janet, who lives in San Francisco, arrives to join this odd household--having fled from her fiancÃ‰ in order to try and decide once and for all whether it's marriage or medical school that she wants to attempt. David is entranced with the much-older Janet: she brings out a courtliness in him that is half pubescent desire, half honor. When she fails him (deciding on marriage), he runs away by himself to San Francisco to persuade her otherwise. And this aborted quest is the book's only real plot complication, coming--somewhat in a rush--during the very last pages. Still, Cunningham writes well of the small epiphanies of adolescence--e.g., what it feels like to fight and feel foolish at the same time. So, though unshapely in its rambling and less effective than Jim Shepard's similar Flights (1983), this is a promising debut--amiable (rather than involving), with isolated moments of real insight.