What is the main conflict in Nightshade by Jack Butler?

Nightshade is a novel of teenage romance, rebellion, and dark fantasy by Andrea Cremer. Cal, a female Alpha Guardian, is able to take the form of a wolf to serve her masters, the Keepers, but her life is completely controlled by them and she grows to resent this fact. One night, as she and her beta, Bryn, are patrolling the mountain near a sacred site, Cal decides to save the life of a human boy by letting him drink her blood after he is attacked and almost killed by a Grizzly Bear.