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Previously on Mi-5
As Mi-5 tracks down the Serbian war criminal responsible for attacks on military bases and munitions transports, Tom (Matthew Macfadyen) puts his career before his personal life, causing his girlfriend Ellie (Esther Hall) and her daughter Maisie (Heather Cave) to leave him for good.
This Week's Episode: "Nest of Angels"
Mi-5's investigation into the potentially dangerous Parkmount Mosque & Community Centre in Birmingham hits a snag when Tom, Zoe (Keeley Hawes) and Danny (David Oyelowo), doing surveillance on the mosque, overhear the torture and maiming of the young Muslim boy they had sent in as a spy. The culprit is Afghan mullah Mohammed Rachid (Qarie Marshall), a Muslim extremist who had been granted the right to live and preach in the U.K. before it became clear he had links to Al Qaeda. Since then, he has taken the mosque away from its more progressive original founder Fazul Azzam (Roshan Seth), and is feared to be breeding anti-Western sentiments. "Every religion has its crooked priests," says section chief Harry Pearce (Peter Firth). "Our question is, is this one a threat to national security?" Tom gets his answer when he interviews the dying boy at the hospital, learning that Rachid has a plan to turn the teenage members of his flock into suicide bombers, a "nest of angels."
Just in time, an opportunity falls into Mi-5's lap when a man named Ibhn Khaldun (Alexander Siddig) appears in London, demanding to speak with Special Branch. With help from GCHQ intelligence analysis expert Ruth Evershed (Nicola Walker), Mi-5 learns that Khaldun was a university lecturer who "was arrested by the Algerian secret service and given a choice -- death, or the dangerous task of penetrating an extreme terror group, the GAJ [Group of Algerian Jihad]." When his cover was blown, a car bomb meant for him killed his family. With nothing left to live for, he has chosen to fake his own death and come up to help out the British. When he reveals that GAJ has been financing extremists in Britain, including Rachid, Harry offers Khaldun a passport and the opportunity to spy for Mi-5. Tom, on the other hand, finds Khaldun's story too likely and considers him a potential double agent.
Mi-5 arranges a custodian job for Khaldun at the University of West Midlands, where he easily makes friends with Muslims connected to the Parkmount Mosque. As Khaldun infiltrated the mosque and gets close to Rachid, CIA liaison Christine Dale (Megan Dodds) comes to Tom with information that her agency not only knows that Khaldun is alive, but that he is working for Mi-5. Tom feigns ignorance, even when Christine plays up the sexual chemistry readily apparent between the two of them.
After Khaldun missing several meets, and having destroyed his Mi-5-issued "ridiculous James Bond" gadgets, Mi-5 starts to worry that he has been playing them this whole time. This is made even more unclear when he very openly tells Rachid that he is working with the British government to take down the mosque but is actually on the side of the extremists. Handing Rachid funds from the GAJ, he earns the mullah's trust completely. But when Khaldun shows up in Tom's bedroom, having barely been able to leave the mosque without anybody noticing, he tells Tom that the next suicide bombing is happening tomorrow, "in the heart of the city." The boy chosen is 16-year-old Abu Hassan (Taahir Husain). Tom has no choice but to take Khaldun at his word, who goes to the mosque the next day, arrests Rachid "under suspicion of keeping false records," and then easily finds the secret compartment hiding the suicide vests. Tom finally gets the bombing location, Warfield Street, after visiting Azzam, who has feared for his life and his religion since Rachid took over.
In a basement, Khaldun watches as Rachid's men strap the suicide vest onto Abu, but reveals his true intentions when he takes out the men and tries to tell the boy that they were the real enemies of Islam. But the brainwashed Abu pushes Khaldun out of the way and emerges from the meeting spot and into the target: A schoolyard full of children. Khaldun is able to shout out a warning for all to evacuate the area, forcing a terrified Abu to run to an empty sports court. As Mi-5 descends on Abu's location, Khaldun enters the court and tries to convince the boy of Rachid's wrongness. Alas, Abu declares that "there is no freedom outside the house of Islam" and pulls the pin on his vest, prompting Khaldun to embrace Abu and sacrifice himself in the explosion.
Hey! I Know That Actor!
The Sudanese-born Alexander Siddig, who plays Algerian secret agent Ibhn Khaldun, starred as chief medical officer Dr. Julian Bashir over 173 episodes and seven seasons of "Star Trek: Deep Space Nine" before appearing on the sixth season of "24" and in such films as "Syriana," "Cairo Time," and the 2010 remake of "Clash of the Titans."