Front Mission 4 has players following two parallel storylines, as they transition between the main characters Elsa and Darril. The game is set in 2096, six years after the Second Huffman Conflict of the original Front Mission. Elsa has recently joined the Durandal team of Wanzers (mechanical battle units), and is sent to Germany to investigate a recent attack on an E.C. base.

Meanwhile, Darril and his team are sent to thwart a political uprising fueled by the Venezuelan governor's recent declaration of independence from the U.C.S. While on route, the team witnesses a plane crash deep in the Venezuelan jungles, and begins to unravel a conspiracy that will eventually bring Elsa and Darril together.

New in Front Mission 4 is a "link system" that allows players to pre-set offensive and defensive battle commands for other Wanzers. Each Wanzer can be customized to provide a specific service or ability during battle, such as air strikes, air drops, repairs, turbo effects, and radar. ~ Damian Francis, All Game Guide