Guardian's End First Book of The People by Richard Baker

Over half a century ago, a cretaure from another dimension was brought into our world to save the life of a child. Contained for generations by a Guardian, it has remained dormant. But now, it's loose, ready to kill without remorse. Today, it threatens a small Midwestern town, but tomorrow, unbeknownst to its captors, it may have the power to destroy the world. Only Talon Kincaid, an agent for a clandestine race known only as The People, stands between chaos and the survival of everyone on Earth.