The episode starts with Heero and Duo conversing on an OZ moon base. Heero wants to go down there and tells Duo bluntly that he is going alone - Duo is too wounded and would only slow him down. Heero takes off for the moon.
The next shot shows the 5 scientists working on the new generation of mobile suits.
We turn to see a mysterious figure setting bombs in an OZ base. It is Major Sally! Sally doesn't want OZ to get Quatre's Gundam so she set a lot of explosives to blow it up. Before she can detonate the explosion, some men stop her. They are Quatre's Arabian bodyguards who have come to recover the stolen Gundam. Sally detonates the bombs and flees.
Sally then boards a mobile suit and fights the incoming OZ mobile suits. The bodyguards load Quatre's Gundam inside a cargo jet and take off with Sally covering their exit.
We turn to see that OZ is training colony members to become future mobile suit pilots. All the trainees are performing poorly but one is extraordinary - breaking every OZ record imaginable. Nikol, who is supervising the training, thinks that the mysterious civilian might be a Gundam pilot (which he is - he is Trowa Barton). To check, Nikol dispatches Duo's Gundam and orders the civilian to destroy it. Trowa doesn't hesitate, blasting Duo's Gundam to pieces.
Trowa is then sent for a private meeting with Lady Une (the one without the glasses). Trowa is excellent in his acting, saying that OZ is the perfect organization for his talents to be of use. Trowa also goes on to talk about how he likes the "dirty" nature of OZ. Lady Une has a mental breakdown and some OZ soldiers, including Lt. Nikol run in to help her.
Nikol (who is very suspicious) pulls a gun on Trowa and tells him that he is to test a new mobile suit. He is escorted to where the 5 scientists are working. The scientists say that the first new mobile suit (Mercurius) is 80% complete while the second (Vayeate) is only 50%.
The biggest feature about Mercurius is that it has a protective force field. We get to see this feature first hand when the Vayeate suddenly powers up (quite mysteriously) its gun to fire at the Mercurius. From inside the Vayeate, Heero jumps out but Trowa intercepts him, pointing his OZ pistol at him. Trowa obviously wants to gain OZ's trust as much as possible. Heero surrenders and the last scene of this episode is of him walking with both hands behind his head.