It takes place in BattleTech universe where the pinnacle of all war machines are huge, heavily armed robots called BattleMechs.

A civil war erupts on Kentares IV after William Dresari, Ian's cousin, betrays the family and seizes the throne under the banner of Katherine "Katrina" Steiner.

Ian fights alongside fellow Resistance MechWarriors, Casey Nolan, Jen McQuarrie, Jules Gonzales, and their commander Elise Rathburn, in various missions.

At one point during the campaign, Ian's uncle Peter is murdered by Duncan Burke, a high-ranking officer in Katrina's forces.

After destroying a disabled but heavily guarded Steiner dropship, Ian and the Resistance move to the Hadra Peninsula, a remote desert region.

Ian is shocked to find that one member of his family survived Steiner's siege of the Dresari palace: his sister Joanna.

Joanna informs Ian of an old armory cache hidden somewhere in the city, invaluable for assaulting the Dresari palace, now the headquarters for the Steiner occupation.

Right before the Resistance prepares to locate the armory, Joanna and her Lance are ambushed by Steiner forces, leaving her wounded and in mortal danger.

Whatever the player chooses, Ian and the Resistance fight one last battle against House Steiner at the palace, putting an end to the war.

Mechwarrior's expansion, Black Knight, takes place several years after Vengeance, and gets its name from the organization of mercenaries the plot revolves around.

The Black Knight Legion fall under the employ of the Lyran Alliance, who wish to reclaim Kentares IV from Ian Dresari.

Eric McClair, CO of the Legion, defeats Maj. Dupree in single combat, destroying her Mad Cat MkII, then proceeds to shooting her ejection pod, killing her instantly.

[11] Chris Kramer of NextGen said of the game, "Knockout graphics and the new gameplay direction aside, this MechWarrior isn't as genre-defining as previous incarnations.

They wrote, "Although it changed the way things work in BattleTech, it accomplished what Crimson Skies set out to do: Open up the sci-fi genre to non-BattleTech-heads.

"[27] The staff of Computer Games Magazine nominated it for their 2000 "Sci-Fi Simulation of the Year" award, whose winner remains unknown.

[40] The Black Knight expansion pack received "generally favorable reviews", although moderately less than the original MechWarrior 4, according to Metacritic.