Covert CIA agent Martian is called back to London Station. An incident in Belarus puts Bosko and Henry on a collision course with Langley. Danny learns a lesson. Someone unexpectedly reappears in Martian's life. Series premiere.

Cast: Michael Fassbender, Jeffrey Wright, Richard Gere, Katherine Waterston, Harriet Sansom Harris, John Magaro, Saura Lightfoot-Leon, Andrew Brooke, India Fowler, Reza Brojerdi, Alex Reznik, Adam Nagaitis, Bilal Hasna, Tom Vaughan-Lawlor, Sabrina Wu, Ambreen Razia, Ray BLK, Emma Lau