Covert CIA agent Martian is called back to London Station.

A spooked source threatens to put an operation at risk.

Martian finds a needle in a haystack and confronts Sami about London.

Henry and Martian run diplomatic interference. Danny walks a tightrope.

Henry sends Owen to Minsk in a hunt for clues. Martian sets a rat trap.

Martian scrambles to unravel Cossack's game. Osman plays his hand.

Bosko is briefed on Valhalla. Martian, Henry and Naomi strategize a play.

Martian's approach doesn't go to plan. Sami makes a startling confession.

Martian buys time with a bluff to Langley. Danny crosses the Rubicon.

Bosko shares a grim truth. Martian makes a devil's bargain.