The witch Rinke rules over the plant Astro with an iron fist. She decides that she needs the super-powered robot, Zangga, to spread her rule to other planets. She learns that Zangga is lying dormant somewhere on Earth and sends her agents, Kats and Kobra, to find and collect him. However, she did not count on the intervention of Betaman and some Earth children who are also looking for Zangga.