The Revelation by Jason Sheil

For most of her life, Fiona Carter has suffered from nightmares. Within them, she finds herself in a desolate world of ruins and smoke, pursued by a terrifying beast that she can never escape. When a strange package arrives in her office, she begins to question the nature of these dreams–and the horrible truth behind their cryptic warnings.

Further west, a middle-aged shopkeeper finds his vacation ravaged by catastrophic events. Lured by visions that may not be real, he descends into the Earth, only to emerge with a strange weapon and an unusual gift. With no memory of the day’s events, he and his family descend once more into the depths, only to find themselves face-to-face with their own nightmare.

Soon their stories will converge, and they will find themselves facing an awful truth. Something is coming, something old and powerful beyond imagination. When it arrives, it will shatter their worlds and tear their lives apart.