Overview: A dark Galactor satellite keeps stealing space satellites and destroying them. It can absorb radiowaves, infrared waves and light, thus it is able to evade any radar. First a satellite investigating Mars disappears, then a communication satellite, then a space ferry and finally a weather observation satellite. Galactor wants to have the hindering Earth satellites out of the way so they can attack the sun with a long range beam cannon from their base on the back side of the moon. Jun and Jinpei board an observation satellite on Nambu's orders to find out who really is behind all this. However, the satellite is attacked, and Jinpei ends up falling into the enemy's hand. Additionally, a satellite to detect new raw material resources is attacked and the Saturn Rubin is stolen. It is said to let the power of the beam cannon increase. Joe uses the small space ship, Swanboat and gets into the dark fortress through the garbage disposal opening. He fails at the first try however, since the Swanboat was defective, and only succeeds when trying again. He detects the enemy base on the moon. The Science Ninja Team sneaks into that base, following the dark fortress. Joe saves Jinpei who had become a hostage. Afterwards, they blow up the base. The dark fortress escapes for a time, but they smash it with the Firebird.