After Sigma's fourth defeat, people began to live in space. The maverick hunters had grown and after years without maverick activity, had believed that the threat was over. Unfortunately, the Sigma Virus in a new form appeared and took control of the space colony, Eurasia. Now Eurasia was set to crash into the earth! If Sigma suceeds, the earth and everything on it would be destroyed. The only weapon that can save them in Enigma, a giant laser cannon. Unfortunately, Enigma needed repair and new parts for it to work properly. X and Zero set out to find those parts, but they only have 18 hours left...