Roberta's employer, Diego Lovelace, was killed, apparently as part of a war between the CIA and the NSA. She vows to punish those responsible no matter what it takes. Fabiola (her understudy), Black Lagoon and Mr. Chang get drawn into the conflict.

Rock accepts the offer to find Roberta before she declares war on the US troops. He tries to solve the puzzle of Roberta's whereabouts, by collecting partial information from everywhere. At the same time, the City Ring (Hong Kong Triad, Hotel Moscow, Italian Mafia, and Colombian Cartel) gather to decide upon what they should do next. The decision is kept secret, but we see Mr. Chang goes to the Church of Violence and is filled in by a CIA member (Eda) about the recent movements of NSA commandos (Alpha, Bravo, and Charlie companies).

Revy seeks information on Roberta’s location and assembles a team, including Rock, Garcia, Fabiola, Shenhua, Sawyer, and Lotton. They arrive to find a fierce conflict involving Roberta, the US Army, and others. Garcia, separated from the group, witnesses Roberta’s brutal combat skills. A soldier, instead of killing her, tries to recruit her back into the FARC. Roberta feigns arousal and wounds the soldier. When Garcia intervenes, Roberta aims a gun at him, believing he’s a hallucination.

After Garcia is rescued by American soldiers, Roberta defeats Shenhua, Sawyer, and Lotton using non-lethal force. Fabiola confronts Roberta and acknowledges her insanity. Garcia, now conscious, pulls a gun on Major Shane, who agrees to Garcia’s quest for vengeance. Roberta attacks but is repelled with help from Hotel Moscow. Meanwhile, Rock arranges for the Lagoon Company to assist the Americans. Revy and Shenhua want to attack the Americans, but Hotel Moscow stops them. Garcia hands the Americans a map from Rock’s envelope, and they head for the coast. Roberta attacks again, but Hotel Moscow intervenes. The Black Lagoon sets sail for the river Mekong with Garcia, Fabiola, the Americans, and the Lagoon Company, while Eda manipulates Roberta into boarding an airplane.

After conversations between Garcia and Rock, as well as Fabiola and Revy, Garcia decides to follow Rock’s plan. Revy experiences flashbacks of her traumatic experience being raped by cops in jail. The Black Lagoon arrives in the Golden Triangle, and the Americans set out on their mission. In the jungle, they are attacked by Roberta using an antique musket, killing several enemies but getting severely wounded herself. Garcia, Fabiola, and Major Shane confront Roberta. Garcia explains that revenge won’t redeem past sins and fires blanks at both Shane and Roberta. The confrontation ends with Garcia kissing Roberta. Meanwhile, Rock shares his motives with Revy and predicts victory over Chang. As the wounded are carried onto the Black Lagoon, Fabiola vents her anger by firing a blank at Rock. Months later, Rock realizes that Roanapur remains unchanged. Roberta, now missing an arm and a leg, lives in Garcia’s mansion and meets the family of her past victim.