Series 10, Episode 6 was the final episode of Series 10 and the final episode of Spooks.
Plot
As Harry is prepared for extradition the team, now consiting of just Dimitri , Erin and Calum , must get him out of custody. Meanwhile, as the deal is signed between Russia and the UK Elena Gavrik tells Ruth she must see Harry as she has information he must hear. Harry and Elena, along Erin, Calum, Dimitri, Ruth and Sasha , go to a disused MI5 safehouse, where Elena informs Harry of a Russia ultra-nationalist plot to crash a plane in London. As Illya arrives Harry realises Elena is a double agent, she tells him that although he believed that he had recruited her in Moscow, in fact she was already an agent, and had recruited him, and that Sasha was not Harry's son, but Illya's.
As Erin and Dmitiri find information on the terrorist and Elena tells Harry apparently everything she knows about the plot, Towers tells Harry he is preparing to have the plane shot down. However, it soon comes to light that the plane may not have been hijacked, and the terrorists are trying to have the plane shot down. Harry threatens to shoot Sasha unless Elena tells him everything she knows, and he eventually decides not to have the plane shot down. However, he needs Illya, a goverment official, to confirm that the plane has not been hijacked, and he says he will not do it unless he can be in a locked room with Elena, alone. Ruth convinces Harry to allow him to do this, and Illya manages to get the fighter jets that were to shoot down the plane called off, but then kills Elena due to the revelations that she is a traitor. Sasha, watching helplessly from behind a two way mirror, breaks into the room with Erin and Dimiti's help, but Illya has already killed Elena. Sasha, believing this to be Harry's fault, takes a shard of glass and goes to find Harry.
Ruth and Harry are outside the safehouse, with Ruth asking Harry to retire with her to the house she revelaed she had bought in the last episode. He agrees as Sasha turns up with the glass. Ruth tries to convince him that she was the one who allowed Illya to be alone with Elena but Sasha tries to stab Harry anyway. Ruth gets in the way and is stabbed. Dmitiri, arriving outside with Erin and Calum, shoot Sasha and the team try helplessly to save Ruth's life. After speaking her final words to Harry ("Harry, we were never meant to have those things", referring to a 'life and a 'home'), she dies. Harry, distraught, holds her body.
Some time later, Harry arranges to view the home Ruth had bought before her death, but not long into it hears her voice from earlier in the episode saying they should "leave the service, together". Harry leaves the house and speaks on the phone to Towers, who tells him he "doesn't expect him to come back to work, ever" (if he doesn't want to). Harry then informs Towers that the ringleader of the Nationalists is being taken care of by a private firm, and it is revealed that Tom Quinn has been sent to presumably assasinate him. Harry then visits a memorial to those officers who have died whilst working, with their names written on a large upright piece of glass. Among the names are 'D.Hunter ', 'F.Carter ','C.Wells ','Z.Younis ','A.Carter ' 'B.Kaplan ', 'J.Portman ','R.Myers ','T.Masood ' and finally 'R.Evershed', who's name Harry harry looks at for some time.
Harry then returns to The Grid, where Erin, Calum and Dmitri are working. He sits in his office, where Dmitri attempt to consul him, only to be stopped by Erin. As Harry sits at his desk reflecting on recent and not-so-recent events his phone rings. He answers with the final line of the series: "Harry Pearce".