In the year 2005, FOXHOUND and the Next-Generation Special Forces (also known as the "Sons of Big Boss") led by Liquid Snake rebelled against the U.S. Government during a routine training mission on a remote nuclear disposal facility and demanded the legendary mercenary Big Boss's remains. With the Army's support, Roy Campbell calls Solid Snake out of retirement once more to infiltrate the stronghold to find out if the terrorists have the capabilities of firing a nuclear missile thanks to Metal Gear REX and to rescue DARPA Chief Donald Anderson and ArmsTech President Kenneth Baker.