A fire in the mountains drive a wolf pack into the nearby desert where they terrorize the local residents. The leader of the wolf pack is Lobo, actually a halfbreed (Rin Tin Tin). When the pack is discovered hunting a herd of cows, a posse gives chase. Lobo leaves his pack to lead the posse away. He is injured and found by a local prospector, Dave Weston (Charles Farrell). The prospector nurses Lobo back to health and the two become close friends. Meanwhile, Weston has made a Borax find in the area. His girl friend May Barstowe (June Marlowe), daughter of a wealthy rancher, is pleased. However the local chemist, Borax Horton (Pat Hartigan), actually a claim jumper, plans to steal the claim.