A werewolf novel with teeth, from the author of Nightlight and Sleepwalker (both 1990). Never has the transformation of man into wolf been portrayed with such psychospiritual intensity as in the narration of Benjamin Byrd, a meek San Francisco psychologist who describes his evolution into a vibrant force of nature. Byrd, an avid ``collector,'' begins his new life when his car clips the dog of the alluring Johanna Fisher. Grateful for his concern, Johanna introduces Byrd to someone who sells him a bizarre set of fangs set in silver. Under their influence, Byrd nightly begins to changeat first unwittingly, then consciouslyinto a werewolf, ``running in the night.'' So enamored is he of his new freedom, power, and sensations, and of his infatuation with Johannasoon revealed as a fellow werewolf, also transformed by the fangsthat Byrd accepts the accompanying bloodlust, including his killing and eating of two people. However, when his wife leaves him for another man whom he vengefully devours, Byrd tastes remorsewhich, along with police pursuit of the ``Night Beast'' terrorizing the city, forces him and Johanna to flee to the Canadian wilderness. There, in a hard but exhilarating plunge into raw nature, Byrd lopes with wolves, fights a wildcat, and eludes hunters; at the same time, he finds himself growing in compassion for all living things, even for the renegade FBI agent who tracks him down and whom he kills. This compassion compels him to return to S.F. to confess his crimes and to destroy the fangs; but, as Johanna warns, ``Our lives are rich with surprise''including a cathartic bloodbath and a final dash for freedom. Overlong, overcomplicated, and shamelessly melodramatic, with cliffhanging chapters and much emoting; but Cadnum's swollen style and poetic prose well suit his hero's Byronic status, helping to make this the most romantic and thoughtful of werewolf novels.