Watch Utah Wagon Train for Free: How to Stream the Movie Online at 123Movies. . Rancher Rex Allen receives a summons from his uncle. an old time frontiersman, that he is in trouble. The uncle has been hired to lead a modern-day band of adventurers on a wagon train retracing the route taken by their ancestors 100 years ago. Before Rex can talk to his uncle, the uncle is murdered, and Rex sets out to find the killer and the motive by taking his uncle's place as the leader of the wagon train.