Damien immediately receives another assignment from his chief and also the Defence Secretary of France, Mr Krüger. He is told that Taha has stolen an experimental neutron bomb that is set to detonate in 24 hours. His mission is to convince Leïto, imprisoned for months, to lead him to Taha's base so that he can disarm the bomb.
Damien attempts to pass himself off as a fellow prisoner and helps Leïto escape to B13, but Leïto sees through Damien's act and abandons him. After fighting off some of the local thugs, Damien locates Leïto and admits the truth. They team up to disarm the bomb and rescue Lola. The pair surrenders to Taha in order to gain access to his base. There, they discover that Taha has rigged the warhead to a missile launcher, pointed towards the center of Paris and is prepared to blackmail the government with it. Taha demands a high ransom, which is refused by Damien's government contact. The pair escape, and while Taha's thugs pursue them, he discovers that the government has emptied all of his offshore accounts in the Bahamas and elsewhere. One of Taha's men asks how Taha will pay them. Frustrated Taha tries to shoot the member who asked him that only noticing his gun to be unloaded. Taha offers money from a safe he possesses. Knowing that with Tahas accounts emptied and unable to have any reason to work for him the thugs shoot Taha. This leaves K2, a more sympathetic character, in charge and K2 has a moment of reconciliation with Leïto, suggesting that peace is possible in the future within B13.
Leïto and Damien fight their way to the tower building holding Lola and the bomb. They are confronted by their final obstacle: Yeti, a substantial henchman left by Taha to block their access to the bomb. Having defeated Yeti, Damien calls his contact to receive the deactivation code, 9293709B13. Leïto recognizes the code as a reference to the bomb's location (92 and 93 are the two area codes of the departements that make up District 13), the day's date (7 September), and the district, B13. Leïto deduces that the government has set them up and the code will actually detonate the bomb instead of deactivating it. He fights Damien to prevent him from entering the code. The timer runs out and the bomb does not detonate, proving Leïto's theory.
The pair return to the government building with the bomb and force Mr Krüger to admit that he had planned to blow up B13 as a means to get rid of it. The confession has been filmed and is immediately broadcast by pirate television transmission across all channels. The pair's actions cause a major scandal that sparks public support for B13. Soon the rest of the government promises to tear down the containment wall and bring back schools and police to B13. Leïto and Damien depart as friends, and Lola kisses Damien to encourage him to visit B13 in the future.