Ming's raiders stage an attack on "The Zarkov Line," an early warning defense system based in an asteroid belt, as a diversion to allow a ship to slip through and kidnap Dr. Zarkov and Dale Arden. Ming intends to force Zarkov to give him information about the Earth's defenses. Flash goes to Mongo to rescue Dale and Zarkov but is captured. Ming's daughter Zara comes up with a plan to allow her and the three captives to return to Earth. Once on Earth, Zara will give false information about the attack in order to sabotage the asteroid defenses.