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.

Henry questions Martian's thinking. Bosko is briefed by Langley on a top-secret operation. Poppy makes a startling discovery. Martian confronts Sami about why she's in London and finds a needle in a haystack, before a heated session with Dr. Blake.