Foaming with rage because Tex and his pards have blown up the load of guns destined to her Sinaguas, Zhenda sets the terrible black panthers against them, brought to America by her ally, the tamer Koster, a nasty fellow who complies with the witch’s wishes, attracted by the mirage of a gold deposit. The beasts are soon defeated and Koster, at the head of a handful of primitive Indians loyal to the witch, tries to lure the rangers into a trap at Crow’s Rock, miserably failing the attack and being killed.