Hell Holes: Demons on the Dalton:

When hundreds of huge holes mysteriously appeared overnight in the frozen tundra north of the Arctic Circle, geologist Jack Oswald picked Angele Menendez, his climatologist wife, to determine if the record temperatures due to climate change were the cause. But the holes were not natural. They were unnatural portals for an invading army of demons. Together with Aileen O'Shannon, a 1,400-year-old sorceress demon-hunter, the three survivors of the research team sent to study the holes had only...