several months after foiling a terrorist attack on Dodger Stadium, FBI agent Darwyn Al-Sayeed is about to start a new life as a teacher at Quantico when he is asked to investigate a new terror suspect. Former cell leader Farik is interrogated by the CIA.

Darwyn struggles to maintain his cover as he assumes command of a new Los Angeles sleeper cell and questions the experience and skill of his new FBI case agent. Farik's interrogators use new techniques to get him to talk.

Darwyn risks blowing his cover to stop one of his cell's operative from taking revenge against a progressive Islamic televangelist; Farik escapes from prison in Saudi Arabia and finds an al-Qaeda safe house.

The cell's new leader, Karrar, pushes Darwyn aside as plans progress for the nuclear attack on Los Angeles; Farik teaches a lesson about the terrorist way of doing business to an American philanthropist at a school in Yemen.

Ordered by the terrorist network to acquire a powerful weapon, Darwyn finds the FBI unwilling to cooperate. Ilija faces a heartbreaking decision as he prepares to flee for Europe. Farik is expatriated to Saudi Arabia, where he can be tortured.

The future of Darwyn's cell is altered when he urges the FBI to intercept a shipment of nuclear material arriving at the Port of Los Angeles - sent by none other than Farik; Ilija faces his past when he arrives home in Sarajevo.

The FBI and Darwyn move to intercept the cell's plans to detonate a pair of nuclear dirty bombs in Los Angeles on the Fourth of July, but their victory is overshadowed by a pair of tragedies for Darwyn.

Farik dispatches a biochemical student on a flight to Vancouver, Canada, to drive a shipment of real anthrax across the Canadian border and down to Los Angeles.

Farik, Darwyn and Christian cross the U.S.-Mexico border at Tijuana to find out why the cell's pipeline of mob funds has suddenly gone dry.

Darwyn blames himself for the tragedies that occurred on the Fourth of July and embarks on a suicide mission to Yemen, where he plans to find and confront Farik using his former cell leader's wife as bait.

Darwyn Al-Hakim is a Muslim ex-con who has just been released from prison and finds his way to an Islamic extremist named Farik, who recruits him to join a terrorist sleeper cell planning an attack in Los Angeles.

Darwyn befriends a pesticide plant worker in order to buy some of his company's product under the table for the cell, while each of the jihadis cope with personal troubles of their own.

Farik and Ilija receive a deadly biological anthrax shipment and prepare for an attack inside a Los Angeles shopping mall. Darwyn's supervisor Ray Fuller become suspicious about the disappearance of a cell member.

The cell hijacks a chemical truck in preparation for Judgment Day, as Farik spends a last night with and bids farewell to his wife, and the FBI prepares to stop the attack.

The cell buys explosives from a white supremacist militia while Darwyn's new handler, Patrice Serxner, tries to prevent the LAPD from blowing his cover in a conflicting investigation.

The cell members pose as Iraqi insurgents-in-training in order to infiltrate and take over a secure warehouse as a new base of operations for Youmud Din ("Judgment Day").

Judgement Day has arrived and Fariq isn't yet out of surprises. A surprise diversion proves effective in allowing the cell to escape their surveilance. A quick thinking Darwyn leaves a clue that will hopefully lead the FBI to the target location in time.

When an Afghan boy arrives at the warehouse looking for training as a jihadi, Darwyn introduces him to a more moderate brand of Islam in hopes of steering him away from terrorism.