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. In a sandstorm he is able to shoot Weston and leave the prospector for dead in the desert. Lobo tries to get a message to May, but runs afoul of Horton. Finally, he is able to bring May to Weston, who are then both terrorized by Horton. Lobo calls upon his pack to eliminate the menace, allowing for the young lovers to finally find happiness. Lobo also finds happiness being reunited with his mate, Nannette.—gr8dane