Spoilers for this episode.
CTU searches for Hasan Numair after discovering that Fayed manipulated the prisoner release to obtain a nuclear engineer. Jack accepts Palmer's request to lead the hunt, despite his doubts about returning to field work. Assad finds a reference to a nuclear weapon among the wreckage at the storage facility. Curtis continues treating him as an enemy, prompting Jack to ask Chloe to investigate whether the two men have a personal history.
Ray Wallace refuses to deliver the component until Ahmed releases someone from his family. Ahmed lets Jillian leave but keeps Scott hostage. Jillian calls the police against Ray's wishes, allowing Jack's team to reach the house before Ahmed can execute Scott. Scott supplies the address where his father delivered the package. Meanwhile, Palmer offers Assad a pardon in exchange for helping stop Fayed and supporting peace negotiations, a bargain Curtis cannot accept.
Chloe discovers that Assad was responsible for capturing and killing soldiers from Curtis's unit during Desert Storm. Curtis takes Assad at gunpoint and refuses Jack's orders to stand down. Jack shoots Curtis to save Assad, then breaks down and tells Buchanan he cannot continue. CTU's assault team reaches Fayed's bomb location too late: Numair detonates the nuclear device in Valencia. Ray and the agents die in the explosion, and Jack looks up at the distant mushroom cloud.