You play Sanjuro Makabe, a Mobile Combat Armor (MCA) pilot and Commander in the UCA Security Force.  Your mission is to locate and assassinate a rebel leader known only as Gabriel.

All of the action takes place either on the planet Cronus or on the spaceship Leviathan.  The Leviathan is the flagship of the UCA and is commanded by Admiral Akkaraju.  Cronus is the only known source of the biologically active material known as Kato, an incredibly powerful energy source essential to the process by which interstellar travel is possible.