|Series 10, Episode 04|
|Air Date||9 October 2011|
|Previous||Series 10, Episode 3|
|Next||Series 10, Episode 5|
Imprisoned Islamic extremist leader Zubier Al-Saad appoints two recently released inmates to commit a suicide attack. One of the released is Ashur Mohali (Asif Khan), an asset from the prison who passed intelligence to Section D; he agrees to help stop the attack on the condition that his daughter be given British citizenship.
However his handlers already kidnapped her to ensure the attack succeeds, and Ashur is now committed to the cause for his daughter's safety. Section D later learns that the attack will take place in Trafalgar Square. When Erin confronts him, she learns the handlers also has her daughter, Rosie. If the attack fails, she will die; Dimitri is able to kill the handler as Ashur is killed by CO19. Meanwhile, Harry must find incontrovertible proof against Coaver. He and Ruth use Elena and Sasha as bait to get to Coaver, but find the mysterious woman instead. However, they find evidence that Coaver was linked. Later, Ruth tells Harry about the offer from Towers; he encourages her to take it, as he does not want her involved in what he plans against Coaver.