Dr. Goodwin is on a botanical expedition in the Himalayas. There he meets Dick Drake, the son of one of his old science acquaintances. They are witnesses of a strange aurora-like effect, but seemingly a deliberate one. As they go out to investigate, they meet Goodwin's old friends Martin and Ruth Ventnor, brother and sister scientists. The group is saved from death in the mountains by a magnificent woman they get to know as Norhala. They are led to a hidden valley occupied by what they name "The Metal Monster", a strange metal city occupied by the metal animate Things Norhala commands. This city is governed by what they call the Metal Emperor, assisted by the Keeper of the Cones.