The campaign follows a story in which the mercenary pilot Monarch fights for the Cascadians in their war of independence against the Federation in a future Earth previously devastated by a cascade of tectonic events in the Ring of Fire.
[2][3] In campaign mode, the player completes twenty-one missions where the objectives can range from destroying enemy planes, annihilating ground forces and bases, and protecting allies.
[8] The game takes place in the indeterminate future of an Earth afflicted by a worldwide volcanic cataclysm centuries earlier, an event known as "The Calamity".
This event not only destroyed modern technological civilization in an estimated 150-year nuclear winter, but also created multiple exclusion zones across the planet along with a valuable geothermal energy resource called "cordium".
By the year 432 AC (After Calamity, a new calendar established after said nuclear winter), civilization has returned to levels comparable to and even surpassing its previous height.
The player controls the game's silent protagonist with callsign "Monarch", who is a member of the Hitman Team in the Sicario Mercenary Corps, which also includes two other pilots: Peter Kennedy ("Diplomat") and Evelyn London III ("Comic".)
After finishing their contract with the Creole Republic, the Sicario Mercenary Corps is hired by Cascadia amid their war of independence against the Pacific Federation.
The Federation forces gained the upper hand in the early stages of the war, to the point of capturing the Cascadian capital city of Presidia.
During a subsequent mission to liberate Prospero, Cascadia's main economic hub, the Federation bombards the city with cordium-enriched cruise missiles when Cascadian victory seems imminent.
Hitman shoots down the bounty hunters and re-establishes communications with Sicario, planning to leave Cascadia behind, but their Cascadian liaison officer offers them an undisclosed "deal" in exchange for their continued support.
Sicario assists the Cascadians with eliminating Federal resistance and re-stabilizing the country, and Hitman defeats Crimson Team in a dogfight above a devastated Prospero.
During the last major battle of the war to liberate Presidia, both sides of the conflict agree to a ceasefire as Cascadia emerges victorious, but Crimson 1 suddenly arrives in a hijacked prototype super-fighter, the 'Project Wingman'.
Overcome with madness from the war and the loss of his squadron, he detonates several cordium-enriched warheads, devastating the city and incapacitating Hitman Team except for Monarch.
Hitman, having ejected from their planes, are rescued by Sicario's SAR unit, and the remaining Federation forces fear their summary execution on suspicion of breaking the ceasefire.
Having suffered irreplaceably high casualties and the immense loss of reputation from using cordium weapon of mass destruction, the Federation faces multiple insurgent movements from other member states, backed by the now-independent Cascadia (now a haven for mercenaries) among other foreign powers.
Set concurrent to the main plot, reservist squadron K-9 is activated in an emergency mobilization and ordered to join the battle over the Bering Strait, despite their inexperience.
In light of the massive losses they suffered, the Federation mobilizes the reserves of the entire frontline territory of Magadan, as Cascadia stages an amphibious invasion into eastern Siberia, led by General Faust.
The turning point comes when Driver performs a daring raid through an underground tunnel, destroying the Cascadian headquarters and putting the entire invasion force in disarray.