Canyon of Danger

Jem Coulter's pa, the sheriff of Goldtown, is away on a trip to deliver a prisoner to Sacramento, and he has left Jem in charge of the ranch—along with Aunt Rose, that is.
No sooner is the sheriff gone then trouble starts—a dead calf, a mysterious stranger, and then Pa's horse, Copper, and his prize rifle are stolen. And Pa's deputies seem unconcerned.
Jem and his cousin Nathan find Copper's tracks end at a dark canyon up in the hills. Jem remembers an old Indian legend Strike-it-rich Sam...