|First seen||Series 10, Episode 1|
|Last seen||Series 10, Episode 6|
Sasha Gavrik is the son of Elena Gavrik and Ilya Gavrik and a FSB officer. He first comes to London as a member of his parent's protection unit. He first appears when he threatens Harry Pierce in Harry's home because he believes Harry is still running his mother and he is worried about her being in danger.Harry, who is not running Elena, realises that somebody is posing as him to get secret information from the cold war period which puts the relationship between Russia and England at risk. At the end of the episode Harry reveals to Ruth Evershed that he and Elena were once lovers and that Sasha is, in fact, his son.
In the next episode a fellow FSB officer tells Sasha that there was an unregistered mobile phone used in the Russian delegation's hotel. Sasha realises that it must be his mother contacting Harry Pierce. He obtains the phone from her while also telling her that she is a traitor and she has made him a traitor too. He convinces his fellow officer not to report the phone by pretending he wants the glory of them finding the M15 spy themselves and then he reactivates the phone and puts it in a minor staff member's hotel room where they locate it. Unfortunately the other FSB officer is suspicious and follows Elena to a meeting with Harry pierce. Sasha follows him, and ends up killing him to keep it quiet. Afterwards he meets Harry and blames him for having to kill his friend who he has known since he was 19. Later he gets rid of the evidence.
In episode 3 Sasha is in his mothers room where he, obviously upset, reveals what he did. He then tells her he must understand why she betrayed Russia and she reveals that the KGB were responsible for the death of her parents which he appears to accept. Later he accompanies his mother to her meeting with Ruth Evershed and at the end tells Ruth that Harry must in future contact him with any information involving Elena. Later Harry tells Sasha that a CIA officer is running Elena but he refuses to tell him who because he doesn't want Sasha to have to be involved. Harry then tells Sasha that he will sort the issue and that Elena's secret is safe with him and their paths never need cross again. However as Sasha is walking away he turns back and asks Harry why he came himself which Harry dismisses.