Steady writing and rich backgrounds give a touch of class to this routine horror/sex hocus-pocus--all about a mutant species living in caves on the Scottish coast. The hero is US tidal-flow expert Don Willis, an alcoholic who goes to inspect the coastal cave waters off Laxford (for which a nuclear reactor is secretly planned)--and is soon joined by wife Mary, a Scots-descended, would-be gothic writer. Arriving while Don's on a surveying trip, Mary moves into a run-down and battered house on the cliffs--where she promptly starts experiencing intensely erotic dreams (though she's never had an orgasm in her married life). So when sexy Jamie McPherson, a workman, shows up to help her get the house in order, Mary is soon seduced--not knowing that Jamie is actually a slimy monster with semen-like pearls of protein dripping off him. In fact, Mary has become the seed-carrier for the Selkies, a race of cave-dwelling Elders whose chromosomes can only be nurtured in an egg that accepts their genetic code! Don is little help to poor Mary, since he's lured into drunkenness by a Selkie in human clothing. Nor do things improve when Mary's best friend Ellie--a paperback editor--arrives and also falls under Jamie's erotic spell. So it looks as if Mary is going to have Rosemary's--er, the Selkie's--baby (as long as she keeps being given injections of that pearl-dripping fluid). And when both Mary and Ellie disappear into the caves, Don and his boss Roger must go into the home pool of the monster-Elders. . . to flush them out to sea by raising a tide barrier. The usual lurid nonsense--but, for those inclined, a somewhat less offensive, more literate treatment than most.