Set after the "Big Shell Incident" of
Metal Gear Solid 2 in 2015-2016,
Metal Gear Solid 4 portrays a world where the restriction of military intervention on foreign soil has been eased, fueling the need for private military companies (PMCs) to fight proxy wars for business purposes. The five largest PMCs are owned by Outer Haven company, operated by Liquid Ocelot. With Liquid preparing to launch an armed insurrection to boost and maintain his financial success, the world is once again in crisis. An aging and disillusioned Solid Snake (aka Old Snake) is deployed to the
Middle East by Roy Campbell to terminate Liquid.