Racism and religious fanaticism make for strong villains in a promising suspense-series debut by the Thurlos (Second Shadow, 1993, not reviewed). When her father, a Christian minister in the Southwest, is found murdered, Navajo FBI agent Ella Clah returns to the reservation -- only to find the community torn between traditionalist and modernist factions, and herself received with suspicion by those who feel she abandoned the tribe for success in the white world. Meanwhile, the FBI investigation is being conducted by a rough-edged Anglo whose troubled history in the community prompts Ella to act as liaison between the bureau, the tribe, and the tribal police, headed by her former father-in-law. Because her father's body was mutilated in a way that suggests a ritual killing, suspicion has fallen on Ella's brother, Clifford, a medicine man whose adherence to Navajo tradition has earned him the respect of many but also brought him into opposition with his father. Before the murder, Clifford, who has now disappeared, argued with his father over the construction of a church on the reservation. Uneasy but resolved to learn the truth, Ella makes contact with her brother through Wilson, his friend -- and her admirer. Clifford believes that their father was killed by skinwalkers, a religious cult that practices black magic and claims the church site as their own. Several grisly occurrences follow: The bodies of deformed animals are found at the church site; ghostly coyotes are spotted; and three men are found slaughtered in a manner similar to the minister's killing -- all of which escalates fears and tension and forces Ella to reconsider the traditional beliefs she discarded years ago. The murderer is chosen believably, but characters are thinly sketched -- especially the heroine, whose external life outweighs her inner one. The real pleasure here is in the complex depiction of cultural conflict and assimilation.