The Zagorath by SJ Sanders

Dragged out to a summer solstice camping trip that she didn’t even want to go on, what began as an intolerable excursion among strangers turns to bloodshed and death as something monstrous awakens from deep within the forest. It kills mercilessly, the air trembling with its roar—and it has set it eyes on her. With every moment that passes, Liv becomes more certain that her death is waiting for her at its claws until she finds that she is being hunted for more than the spilling of blood. The creature wants her. Captured, she is at the mercy of its hunger. It is only in the midst of it that she discovers that giving in to its desire—and the passion it rouses in her—just might save everyone.