Still steaming over their surprise defeat, Baron Garoga sends out another, much larger scout team to Earth. In the daytime, their arrival on the lush water filled world doesn't go unnoticed. A local man and boy witness the glowing red missile streak down from the heavens and smash into the countryside below. They pack up their telescope and try to find where it landed, but by the time they locate it, the Garoga creatures have scampered away. All that is left are bits and pieces of their shattered vessel. For some strange reason, the man feels that Yoichiro (really Zone Father), might be able to identify the strangle metal, since he'ss a toy maker. As they prepare to leave, another peculiar man arrives on the scene and tosses a small transmitter into their car. Listening to their conversation, Detective Jo Takeru gathers information about the recent objects that are falling from space.

While looking over the alien metal and some photos taken by the man’s telescope camera, Zone Father comes to the conclusion that the Garoga are making another attempt at Earth. As this horrifying truth of the Garoga finally reveales itself, elsewhere Akira and the little boy are playing around with a remote control boat. Two agents in human garb nearby take control of the vessel with their own control unit and send it to attack the little boy. Hitting him in the head the child is gravely wounded, forcing Zone Junior to find help. Luckily for them both, Detective Jo is nearby and brings them both back home.

Zone Father, sensing nearby danger, calls for Hikaru to return to the house immediately. His trip would be delayed, however, as he mets a police roadblock. Stopping for them to ask some questions, one of the police officers takes the opportunity to place a bomb under his car as Hikaru drives away, completely unaware of what the disguised malice filled aliens had done. Fortunate for him, an old woman is crossing the road, forcing the-would be hero to halt his car and shake loose the bomb. He then drives away, leaving the destructive device in the dirt where it would later explode as the Garoga agents were attempting to follow him.

Back home, the little boy and Akira are transferred to a hospital. The boy’s run in with the haywire toy boat resulted in his need for immediate surgery. Both boys are placed side by side on tables and prepped for the doctoral work. In reality, the doctors were three more Garoga agents in disguise. Preparing to stab the life out of both children with a scalpel, their plans fell apart as a gunshot rang out through the window and stuck one of them in the arm. Charging forth from the shattered glass, Detective Jo fought and defended the boys from the murderous spies. This gave Akira enough time to send out a S.O.S with his Zone Communicator, which soon brought Hikaru and Hotaru to their aid. Fighting side by side, Hikaru and Jo eventually send the cowardly creatures fleeing. Quickly the three Zone family members take off in hot pursuit. Transforming themselves and their vehicle into their real villainous forms, the Garoga make a mad dash to get away. However, the heroes too transform, along with their car. Flying in the Mighty Liner, they almost catch up to the black vehicle, yet fate intervens and a Monster Capsule rains down from the night sky and explodes.

Setting its clawed feet on the soil of Earth, Destro-King attacks the Zone family, allowing the Garoga agents to escape. Zone Fighter has little time to worry about the getaway car, and is forced to transform himself into his giant form to battle the newly arrived Terro-Beast. Attacking with unbridle fury, it wasn’t long before Earth’s savior unleashed a flurry of missiles from his bracelets. To his surprise, Destro-King still stood! The creature had survived his most powerful attack and in his weakened state he was a sitting duck. The two headed cackling demon would have won if not for Zone Juniors and Zone Angels interference. Taking to the skies, the duo blasted off one of the leviathan's heads and then used their beams to restore power to their fallen comrade. Rising from the ashes, the silver warrior launched another assault on the creature, which soon led to its destruction. Earth was safe once again from the Garoga Empire.