Priest, a young Britisher with a flair for finding quietly tantalizing sci-fi hypotheses, works some clever variations on the well-worn notions of the dream-world and alternate world. ""The perfect lover"" is an imaginary place--Wessex, product of a 1985 experiment in group illusion being conducted near Dorchester. The participants have been hypnotically projected into a ""future"" which has been laid out along general guidelines but then allowed to develop into the sum of their communal imaginings. Their unconscious bodies rest in elaborate life-support systems while they go about their Wessex lives sealed off from any memory of ""previous"" existence. The world they have made--an island cut off from England by the ""Blandford Passage"" and the ""Somerset Sea""--is a lovely resort, serenely divorced from Soviet England and its concerns. Four years into the project, a new director is brought in: Paul Mason, a cunning sociopath bent on reshaping the imaginative consensus on which the idyll of Wessex rests. Only two participants are able to resist his control: Julia Stretton, his former mistress, and her new lover David Harkman, who has developed a strange immunity to the post-hypnotic triggers which periodically withdraw the others from their trance. Priest develops his ingenious premise with unobtrusive grace, but somehow not with the thoroughness it deserves. The idea really demands a longer, slowermoving narrative with a larger weight of detail. Perhaps the chief flaw here is the character of Mason, a particularly flimsy cardboard villain where Priest's provocative design demands a figure of real menace.