The darker vision and sexual ambiguities of this erotic, ironic tale about a menage a quatre in a New England university town foreshadow those of The World According to Garp; but this very trim and precise novel is a marked departure from the author`s generally robust, boisterous style. Though Mr. Irving`s cool eye spares none of his foursome, he writes with genuine compassion for the sexual tests and illusions they perpetrate on each other; but the sexual intrigue between them demonstrates how even the kind can be ungenerous, and even the well-intentioned, destructive.