The Dark River

At the start of the engrossing second entry in the Fourth Realm trilogy, the Brethren continue to control civilization through a computerized information system, the Vast Machine, and a host of offshoot surveillance technologies. Opposed to the Brethren are the Travelers, an ancient clan with the mystical ability to slip in and out of several dimensions. The Travelers are guarded by Halequins, a warrior caste with sharp swords and ferociously lethal skills. In the Cain and Abel story at the book's heart, the quest of two Travelers, brothers Gabriel and Michael Corrigan, to find their legendary father has split them irrevocably: Gabriel fights for the forces of good, Miahael has turned to the dark side.