Empyreax: The Rise of Cà Rá by Scott Frost:
 
When Jack Young receives news of his estranged father's death, he's relieved to be freed from the ramblings of a madman. Heading to the town of Stone Creek, he prepares his father's eccentric mountain cabin for sale, but discovers a secret tunnel beneath it that disrupts his plans.

Hidden away in an underground cavern, he finds Cà Rá, a young woman with cosmic origins who claims to be his father's friend. As guardian of the mysterious Empyreax device, she warns Jack of an imminent danger that will annihilate the planet.

But Jack's not the only one who's arrived in town. Demi Carver-a doomsday cult fanatic with an interstellar secret of his own-is hunting for the Empyreax and will kill anyone who gets in his way.

Bound by an oath to protect Jack, Cà Rá is his last defense against Demi's growing dark forces. When she is captured, Jack finds himself reluctantly drawn back into his father's world, teetering on the edge of reality.

Fighting back against the clutches of fate, he must unravel the tangled clues his father left behind before Demi can ignite the spark that will torch humanity.