In the year 2171, fifty years after the events of Front Mission 5, the world's major powers have extended their rivalry into orbit, each building enormous structures called orbital elevators while watching each other through a growing network of surveillance satellites. USN engineer Dylan Ramsey is testing a prototype wanzer for Diable Avionics on Long Island when unknown forces launch an assault on New York City and its orbital elevator, Percival. Worried about his father at the National Strategic Research Laboratory, Dylan takes the prototype into the city. He battles through the attackers and reaches the NSRL just as missiles level it. Engaging the attacker — Marcus Seligman of the Apollo's Chariot — Dylan's fight is cut short when Percival collapses onto the city. In the aftermath, Dylan is recruited into the USN Army as it prepares for war against the Oceania Cooperative Union.