Hebe Weenolsen
The Forbidden Mountain
1983

"Set in prehistoric Britain, the story is based on a legend that was passed down by oral tradition through more than two thousand years until put into writing by monk Geoffrey of Monmouth around the year 1136. Its central event, the transportation of the Bluestones, describes the origins and building of the world-famous ruins at Stonehenge-or, more precisely, the building of what is now known as Stonehenge II, or Bluestonehenge.

...a story of greed, vengeance, love and human tragedy, of the compelling superstitions of the age, of implacable hatred and calculated betrayal and a final, savage nobility.

The hero, Gwynnan, is a member of a peace-loving, earth-worshipping Island tribe. The central villain in Hancar, the treacherous and murderous prince of the invading Beakermen, who worship the sun. Somewhere between the two is Hancar's father, the all-powerful King Sinnoch, whose ability to distinguish between good and evil interferes with neither his greed nor his ambition. And it is Gwynnan's misfortune to find himself in love with Sinnoch's wife, the beauteous young Oralu..."