Legend centers on Saul Buchanan's rise to prominence at the head of the Hundred Families. Starting off with the Patriarch at his nadir, as he loses his bison herds to the Monster Army, it shows the Hundred Families before their unification under a common banner. Buchanan's repeated attempts to rally them have fallen on deaf ears, as the culture of rugged individualism, rooted in mistaken worship of their survivalist ancestors, and the latest attempt goes no better when Morton Reed, patriarch of the Reed family, and Henry Avery, walk out on his latest attempt to pass a Colorado Constitution and unite the disparate families against a common enemy.
Looking to the future, Buchanan and Sergei Greatski decide on a gambit. Buchanan strikes a deal with the Monster Army, after meeting one of their patrols and being brought to the Bizarre. Detcord sown into his jacket a guarantee of his survival, he trades strategic information on the Avery power plant powering Colorado Springs, in return for a portion of the tribute the Monster Army will extract from Colorado Springs once they take it. With their identity concealed by Monster Army masks, Greatski and Buchanan participate in the assault and seize the power plant for the Army. Buchanan learns a crucial fact about the Army, that their organization depends on Skinchangers, officers equipped with special radios that allow them to communicate without attracting enemy attention.
Medusa realizes Saul's real identity and forces him to execute Colorado Springs' guards taken prisoner. Though he acknowledges it as a complication, he continues with the next part of his plan: Rallying the Springs. To his surprise, Henry Avery supports him and proposes naming him the general in charge of the operation, with Kristen Avery, the daughter of Henry, attached to his strike force. Preparations and plans are made, and Saul heads the strike force to the power plant. He is believed lost in the fighting, as the Monster Army ammunition dump he attacked as a priority target detonates prematurely. The sorrowful Henry Avery, in the communal meeting after the attack, decides to take up Saul's cause and unite Colorado under his banner.
However, Saul isn't dead. Realizing that the Avery's are up to no good and will try to kill him in one way or another, he prepared for the opportunity. The rigged detonators Avery provided are kept as evidence of wrongdoing, which Greatski presents to Althea Dorsey, just as Saul heads into the communal hall to interrupt Henry's speech. Having disposed of Medusa, who tried to kill him with her goons as he and Greatski hid in the wilderness after the explosion at the ammo dump, the last obstacle is the Avery patriarch. The confrontation turns violent as Avery attacks the wounded, tired Buchanan, and eventually is slain in honorable combat, laying the foundation for Patriarch's legend.