Science fiction? Supernatural? Parapsychological? No matter. Whatever you call the particular twilight zones that Kate Wilhelm explores in these eight all-possessing stories, you'll realize in no time that she is writing people stories: Wilhelm uses her outer spaces and dream states and strange creatures as apt projections of inner turmoils and nameless fears--like the nameless fear that makes an apparently perfect planet uninhabitable in ""Planet Story."" And, though it's possible to work out clinical diagnoses for some of the strange behavior here--two antagonistic strangers snowed in at a heat-less bus station, a hausfrau-laborer who abandons her dreary life for Mars and beyond-Wilhelm has that precious knack for navigating between mystification and over-explanation: she almost always leaves you wondering but satisfied. Only a trendy anti-TV satire (a game show puts contestants through life-or-death ""Crisis Therapy"") overstates its message, though the focus here is really on marital solace (the TV-watching couple ""held hands as they drifted off to sleep""), just as it is in the delicious ""State of Grace"" (wife adores near-invisible backyard creatures, husband tries to kill them) and ""The Hounds"": a wife shoots two sensuous, silvery mystery dogs who embody her unhappiness and her memories of warring parents, and--in a conscious echo of the TV tale--this couple ""went to bed early and held each other hard until they fell asleep."" Wilhelm's most difficult stories are her most naturalistic ones, with the inner turmoil out on top: ""Symbiosis"" gives us total marital breakdown (veiled for years by domestic high spirits), with its inherited effects; and the title story, slightly overwrought and overworked, nevertheless finds a freshly haunting expression--via dream research--for the need to say final goodbyes to childhood. Combining the up-lift of the unknown with the down-pull of essential human traumas, Wilhelm has come out with a gravitational marvel of a collection.