Zeon's Secret Mine is the eighteenth episode of Mobile Suit Gundam. It aired in Japan on August 4, 1979 and in North America on August 14, 2001.
On Earth, Amuro has hidden the Gundam for the night and taken refuge in the ruins of a small abandoned desert town. As he sits eating in front of his camp stove, he hears the sound of a low aircraft approaching. Startled, he picks up his gun and races to the doorway to see a mobile armor, the Adzam, with M'Quve and Kycilia at the helm. Amuro watches it until it passes out of sight.
Meanwhile, White Base sits at the edge of another town. The crew discusses what they'll do with Amuro should he come back. Kai offhandedly remarks that deserters usually get the death sentence, which upsets Fraw Bow. She accuses Kai of being a liar, but Bright says that it's true. Sayla states that they'd execute Amuro if they had to. Fraw can't believe what she's hearing and snaps at everyone. Mirai and Ryu offer consolation, but grudgingly admit that Amuro's actions have been pretty selfish up to that point.
The next morning, Fraw Bow sets off in a small jeep to begin to search for Amuro. She soon finds a set of large footprints in the sand, which lead her to the small town that Amuro is using for his hideout. Hearing her approaching, Amuro pulls out his gun and startles her as she finds him. As the two walk to the Gundam, Fraw Bow tries to convince Amuro to come back to White Base, but accidentally lets slip that the punishment for desertion is death. Amuro is convinced that all the crew really cares about is the Gundam. Disgusted, Amuro hops in the Gundam and walks off. Fraw follows in the jeep.
Back on White Base, Kai, Hayato, and Ryu are disassembling, cleaning, and reassembling pistols. Kai complains, but Hayato says that they're not moving until Fraw Bow gets back. Kai wonders if they couldn't just tell her where they're moving to, and is informed that although Central Asia is technically a neutral area, it's still crawling with Zeon and wouldn't be safe for a Federation soldier, never mind a girl like Fraw.
In the meantime, Fraw continues to follow Gundam across the desert. They soon find a large Zeon mining base. In one of the base's observation towers stand M'Quve and Kycilia, who are discussing the resources obtained through the base. Fraw says they should contact White Base, but because they can't use the radio, Amuro tells Fraw to head back in the jeep while he continues his reconnaissance.
On White Base, Mirai and the others continue to wait for Fraw's return. Some of the crew below deck wonder if Amuro has defected to the enemy since he'll be treated as a hero for turning over Gundam. Amuro continues to spy on the base, and comes to the conclusion that it is the mine that General Revil wanted to attack on Odessa Day. Amuro looks over the base's armaments, which are sparse, and decides that he can attack the base with just the Gundam. He figures that if he is able to destroy the mine, the Federation Army won't have to mobilize to attack it, and then Bright and Mirai won't bother him anymore. Amuro begins his attack.
Kycilia figures this would be an opportune time to test the Adzam's abilities as well as get a good look at the Federation's new mobile suit. Amuro continues to attack the base and destroys its laser turrets. The Adzam soon rises from the ground. The Adzam launches a small capsule on the Gundam, which Amuro immediately shoots down. This causes a golden power to cover the Gundam. The Adzam then issues a small conical device which launches wires around the Gundam and are charged with an electrical current. Gundam is required to use almost all of its energy to keep the cockpit cool, preventing it from moving.
Meanwhile, Fraw Bow has finally managed to reach White Base, and tells the crew about the mining base. They check their map, and note that the location of the particular mine that she mentioned doesn't exactly match up with the coordinates given by Revil. However, they decide to move forward and check it out anyway. Back at the mine, Amuro is still fighting the Adzam. Hoping to finish off the Gundam, M'Quve lowers the current, which permits Amuro to destroy the conical device and free Gundam. Amuro jumps on top of the Adzam and M'Quve's attempts to shake him off fail. Not wanting the Federation to get a hold of the base's secrets, Kycilia orders the entire mine destroyed. The Adzam manages to escape after M'Quve triggers an explosion destroying the base.
Thinking that he's destroyed the base that the Federation wanted to attack on Odessa Day, Amuro gets out of the Gundam and explores the ruins. He descends into the lower level of a half-destroyed building where he discovers that this is just one of many Zeon bases. Climbing out of the rubble, Amuro comes across a wounded Zeon soldier. He retrieves some water from a nearby pipe to give to him and then makes him comfortable, handing him a flare to use to attract help. As he leaves, the soldier gets Amuro's attention and tells him that if he is the pilot of the mobile suit then he doesn't have enough lives to go easy on the enemy. Amuro thanks the man for his advice and leaves.
White Base finally arrives and surveys the smoldering wreckage of the base. The crew is shocked and appalled at the amount of damage done by the Gundam's attack. Mirai remarks that this mining base wasn't even the Zeon's main base, which causes Ryu to remark that because of this, the enemy will be even more entrenched when the time comes to attack the actual main base. Fraw is simply dismayed that Amuro even attacked it at all, and flees from the bridge. She jumps into the jeep and speeds away from White Base, tears in her eyes.
- Mecha Introduced: Adzam