Danny promises a child that he'll open a cold case, the death of his firefighter father. Meanwhile, Jamie saves a baby from a burning building but worries that his new found fame as a hero in the press jeopardises his job.
As Sherlock reels at the reappearance of his former lover, Irene Adler, a series of flashbacks unravel the tumultuous events that led to his downfall into addiction.
Elizabeth and Philip come together to deal with a mission gone wrong, but struggle to reconcile their ideologies; Stan welcomes a Soviet defector to America; Nina acclimates to her new living arrangements.
Danger mounts for Elizabeth and Philip as they get closer to the inner circle of the CIA Afghan Group; Stan monitors Zinaida; Agent Aderholt challenges Agent Gaad on a crucial operation; Arkady tasks Oleg and Tatiana with gathering intel.
Philip and Elizabeth are thrown off balance when things with Tuan take an unexpected turn. Henry makes a startling proposition, and Stan has a disturbing encounter with Frank Gaad's widow.
