In a pure wish-fulfillment fantasy, 26 teens try running their own town. Maria's unexpectedly inherited millions finance the venture; she and best friends Mimimi and Seppy are bright, good-looking, cool, possessed of buoyant wit, and superior to their parents in wisdom and competence. Seppy's room is a camper decorated as a gingerbread house, parked in the back yard and private, available as transport. ""Mariasburg"" works well at first--Maria is a master at getting cooperation, and everyone appreciates the chance for self-responsibility and a breathing space before college. But although the group manages to evict two druggies and impress visiting parents, outside threats (a manipulative sex-mad sheriff plus a nearby community of violent religious fanatics) provide a chance for action and suspense as the kids are involved in strategy, siege, heroism, and hairbreadth escape. Feminists may detect inadvertent ironies: Maria's administrative talents come from her father, and the kinky sheriff is slightly titillating as well as abhorrent. The conclusion is abrupt--why not revel just a bit in the final triumph? Still, Thompson--who is as witty as Zindel but somewhat less frantic--provides a lively plot, engaging characters, and sure entertainment.