Dave vs. The Monsters. Emergence (David Hooper 1), Paperback/John Birmingham

When an oil rig drills too deep, it unleashes a torrent of nightmares - the creatures of legend, always thought to be figments of our imagination, are now a very real threat to the survival of humankind. But when he kills a seven-foot demon, Dave Hooper - a middle-aged oil-rig safety manager - is transformed into an honest-to-god monster slayer.