Crosstime

An orphan, Blake Walker has never really known who he is, and his strange flashes of intuition have always set him apart from those who raised him and everyone else he has known. Acting on one of those flashes, he prevented a murder. But neither the assailant nor his intended victim were from the world Walker had always known, and he had stumbled onto the greatest secret of the ages. Our Earth is only one of an infinite number of Earths, each with a slightly different history from the other...