Ellen is worried about her husband, successful children's book author Ben Sterling. Ever since inheriting the family house in isolated Stargrave, his old childhood demons have been reemerging. Ben's father was crazy - he traveled to the ends of the earth researching legends of the midnight sun, and committed suicide by stripping naked in a snowy clearing - and Ellen is beginning to be afraid Ben might just be a chip off the old block.
But soon something starts scaring her worse - Ben's insistence that an eldritch god is awakening in Stargrave to reshape the planet in its image seems less a fantasy than when he and his crazy father first started spouting the idea. Stargrave is changing. It's getting colder. More isolated. The trees, the snow, the very frost itself, increasingly appears to be rearranging itself into that god's own image. Which means, perhaps, that Ben isn't a madman at all, but a genuine prophet - and if that is the case, then the end of the world is at hand...
This is one of Campbell's best, and that's saying a lot. The novel is uneven, and could have been structured better, but overall it's a steadily mounting masterpiece of menace. It's most reminiscent of Algernon Blackwood and H. P. Lovecraft, in that its horror is genuinely cosmic and never truly seen except for the effects of its presence. Dramatically, it's highly reminiscent of Stephen King's The Shining, in that a snowbound woman protects her children from her increasingly unstable (and quite possibly dangerous) husband, with an unseen supernatural being influencing events from the frozen shadows.
Sadly - like most of Campbell's best work - this book is out of print, but it's well worth trying to find anyway if you're a fan of well-crafted, creep-up-behind-you horror.