Evelyn's salvage job for Dante turns into a bloodbath when the Antithesis swarm the undercity. She crawls through a ventilation duct to escape, finds a priceless fabricator, and emerges to a massacre. She grabs a fallen SMG and kills three Model Threes in a desperate firefight. The act triggers her awakening as a Samurai, granting her an AI named Nyx and a point-based catalog system. She drags the wounded Dante to Leah's clinic, where she purchases her first weapon, the CAR-156 battle rifle, and begins to understand the terrifying scope of her new power.

Evelyn fights her way across the undercity to rescue her family, discovering that the Antithesis have infected hundreds of civilians with parasitic Model Sevens. She is forced to execute the infected crowd, a traumatic act that hardens her resolve. She secures the Terminal, a massive trading hub, and rescues her friend Jane. She meets Humboldt, another Samurai in power armor, and together they track the Antithesis to a hive in the scrapyard. A brutal battle against a Model Twenty-Six ends with Evelyn's giant bear bot, Bob, tearing the commander apart, allowing the team to destroy the hive and end the immediate threat.

Evelyn is called to Seattle to help evacuate a city overrun by a massive underwater hive. She upgrades her forces with a mobile creation engine and faces her greatest challenge yet: a colossal Mantis Shrimp Antithesis that destroys her best bot, Bob, in a single blow. She improvises, salvaging a railgun from a downed mech and using a sonic grenade from a friendly Samurai to finally kill the beast. The battle earns her a massive point windfall and cements her reputation as a resourceful and terrifyingly effective combatant.

Returning home, Evelyn discovers the Guiding Light, a dangerous cult that nearly destroyed the undercity six years ago, is resurgent. She also learns that a rogue Samurai is supplying them with weapons. After being shot by a Class I pistol during a tunnel ambush, she vows to hunt them down. She begins flooding the undercity with surveillance squirrels and planning a school for local children, aiming to break the cycle of gang violence through education. Her family and friends rally around her, and she starts to build a new future from the ashes of her old life.