Heero and Quatre are saved by members of the Treize Faction, consisting of soldiers still loyal to Treize, and meet the engineers, who explain that the Wing Gundam Zero uses a system known as ZERO, which increases skill but takes away free will, thus driving the pilot insane. They are captured again by OZ soldier Trant Clark, who forces Heero to test the ZERO System to gather data. Quatre stops Heero before his insanity destroys the abandoned colony and the pair escape to Earth.