Fever by Jordan L. Hawk

Tired of living as con artists, Colin Muir and his brother Doug join the stampede to the gold fields of the Klondike. If they can strike it rich, they’ll be wealthy beyond their wildest dreams.
But nightmares await alongside the gold. On a claim owned by a dead man, haunting voices call out from the forest, and strange tracks surround their cabin at night. In the midst of the arctic wilderness, a primordial evil has awakened, one that wants not just the brothers’ lives, but their very souls.