While Morgana sets a horde of werewolves loose to destroy Britain, Merlin and eighteen-year-old Arthur must rally warriors against three overwhelming enemies, without unleashing an even greater evil.

When U.S. deputy marshal Merlin Fanshaw mistakenly kills an innocent boy during a bank robbery, he abandons his career and rides off into a vast and mostly empty region known as The Big Open. Hired as a cowhand by ranch woman Billie Hart, Merlin is drawn into a deepening conflict between Billie and a ruthless cattleman who will stop at nothing to possess her ranch. When violence threatens, Merlin takes a stand, and exorcises the ghosts of the past.