destroy. The initial battles are costly to the Brotherhood. Outgunned and outmanned, the Brotherhood is overwhelmed outside of St. Louis. There General Barnaky, head of the Brotherhood, is captured by the Toccomata, leader of the mutant army. Although the Brotherhood is able to withdraw, they remain under constant attack. A squad dispatched to destroy a munitions manufacturing plant instead finds a laboratory dedicated to curing mutant sterility. The Brotherhood claims the lab in order to use it as a future bargaining chip. A few days later, at the ghoul town of Gravestone, in the ruins of Kansas City, Brotherhood scouts find an intact nuclear bomb. The Brotherhood defends the town from several mutant encroachments, and they are soon able to remove the weapon to a safe bunker. Brotherhood scouting reveals the base of the mutants to be at Osceolla, near the ruins of one of the wrecked Brotherhood zeppelins. A squad fights its way into the base. Inside, they find Toccomata, who is dying. He reveals that General Barnaky had been lost to an unknown menace from the west that was too powerful for even the mutant army. As the squad enters the room where the mutant leader was hiding, they find Paladin Latham, one of the leaders of the Brotherhood air convoy. He tells the squad that after crashing, he fought Gammorin in hand-to-hand combat for leadership of the mutants. Latham won, but a head injury from the battle became infected, and he soon became delusional. Latham assumed the identity of Gamorin, and led his new army against his old allies. The squad kills Latham before he can endanger the Brotherhood even more. Soon, the menace from the west reveals itself: a robot army is sweeping across the American Midwest. The reavers, a cult dedicated to technology worship, is caught between the Brotherhood and the robots as the two armies clash in Kansas. Although the Reavers try to wage a two-fronted war, they are soon beaten, and seek sanctuary among the Brotherhood in exchange for an electromagnetic pulse weapon. The Brotherhood agrees, and a squad armed with the new technology destroys a robot repair plant as they push into Colorado, towards Vault Zero. It is revealed that the robots are originating from Vault Zero, and are being directed by an enigmatic enemy known as the Calculator. Evidence uncovered by the Brotherhood points to a catastrophic experiment in the Vault