In this, his fifth novel, Campbell steps away from the murky, muted horror of his most recent work (Obsession, 1985), which relies more on abnormal psychology than occult evil, and delivers instead a terrifying atmospheric thriller of explicitly supernatural dimensions. Moonwell, a sleepy town in England's Peak District, draws its name from a cave that dominates the surrounding moor. Every Midsummer Eve the townspeople, echoing ancient Druid Customs, decorate the cave with floral designs. But not this year: a spellbinding Christian evangelist, Godwin Mann, has come to Moonwell to put a stop to pagan festivities. Most of the townsfolk embrace Mann's semi-fascistic message. Only Diana Kramer (a schoolteacher), Eustace Gift (a mailman and stand-up comic), Geraldine and Jeremy Booth (liberal-minded booksellers), and a few others battle the rising fanaticism of the True Believers. It's no accident that these people all work with words; this is among other things a parable about the dangers of suppressing the free commerce of ideas. When Mann descends into the cave to squelch the pagan forces that lurk there, he encounters instead an evil being of tremendous power who invades him body and soul, changing him into a humanoid ""spider made of moonlight,"" with long spindly arms and reptilian eyes the size of shirt-buttons. Notwithstanding this horrible transformation, the evangelist continues to mesmerize the locals. Meanwhile, darkness covers the town, the phones go dead, deliveries from the outside world dry up: Moonwell has been cut off, turned into an staging ground for the advent of cosmic horror. Diana, in a vision (the one weakness in an otherwise steel-lined plot), learns that the Mann-beast is an ancient lunar being that came to earth and hunted human prey until trapped in the cave at Moonwell. It lies at the root of all human fears; attempts to supplicate it gave birth to religion. Free at last, the monster intends to wreak revenge by detonating nuclear missiles stationed nearby; only frail Diana can prevent the end of the world. Campbell grounds this bold, far-fetched story with ominous, moody descriptions of nature (""Patchy clouds lumbered across the sun. The sky flickered like a smoky fire""), characters that fit well with anyone's nightmare of small-town life, and, like mad piping from Pan, the leitmotif of the baleful moon, a giant skull ""grinning its crumbling grin."" The violence that flares as the Mann-beast grows is blunt, frightening, but apropos. In every respect, Campbell's best.