Technological data on the nuclear-armed walking tank, Metal Gear, leaks onto the black market. The legendary hero, Solid Snake, sets out in pursuit of a tanker carrying a new Metal Gear prototype. But Snake falls into a trap and is believed lost along with the tanker at the bottom of the Hudson River. Two years later, terrorists seize control of the Big Shell, an oil spill cleanup facility. Responding to the crisis, the government sends Raiden, a new recruit within the special ops unit FOXHOUND, to infiltrate the Big Shell and rescue the US President.