This book is about Grays (aliens) breeding with humans and trying to take over the world. Below is the back cover description.
Book 3 - The Half-Breeds
Now on the run with the book stolen from the Grays in hand, Jay, Nina, Ishmael, Sunny and Lydia find themselves in the mountains beyond Brookfield as Old Mary’s prophecy comes together. David, their leader is gone and they are lost. Jay must step up and lead them, although he is reluctant to do so, and some refuse to follow.
Together, this band of kids will discover how to fuel the power of the Paragon just as Jay’s mother, Tara and his Aunt Vicki had years before he was born, and attempt to intercept the Gray’s plan for the future of the planet.
But time is short. The Grays are closing in, sending half-breeds to scout the area. Even though they have only just begun to train, they must now make a choice, ready or not. If they don’t, the Grays will make it for them.