Weeks after arriving in Colorado to start a new farm, the Hollowell family is looking at disaster when fifteen-year-old Owen witnesses the theft of their mules. Learning that Hercules and Peaches will likely be sold to the mines, Owen sets out to track the rustler over the mountains. It’s all Ma can do to hold back little brother Till, who’s more than a handful.
The outlaw’s trail leads to Telluride, the turbulent “City of Gold.” Owen gets help from a resourceful girl named Molly and dubious assistance from Till, who shows up on the train from Durango.
Telluride’s notorious marshal finally takes an interest when he identifies the rustler as one of Butch Cassidy’s Wild Bunch. The lawman leads Owen and Till on horseback into the canyon country and all the way to Robbers Roost.