Wandering researcher of the supernatural John Thunstone--a long-time Wellman hero, like Appalachian balladeer Silver John (The Hanging Stones, 1982)--returns in this quiet, well-developed, but blandly unexciting yarn. Thunstone visits the English hamlet of Claines to investigate Old Thunder, a huge, ancient figure cut into a chalk hillside, and its associated menhir, the Dream Rock. In an ancient pagan ceremony, the villagers will turn the Rock at midnight on July 4th, and already things uncanny are stirring: in the dark, Thunstone is transported back into the world of Old Thunder's ""paleolithic"" builders and worshippers; knowledgeable aristocrat Gram Ensley, who claims descent from the same paleolithics, is preparing for some dire, triumphal event; vicar David Gates preaches thunderously against paganism and the Rock-turning ritual. And it turns out that the paleolithic god Gram, having decided to take a 10,000-year-long nap, will awaken when the Rock is turned--so Thunstone must thwart the malign Ensley and prevent the monstrous Gram's reappearance. With lots of fairly persuasive English ambience: pleasant but inconsequential.