Knightley (Pirates of the Caribbean) stars as Helen Webb – devoted mother, wife, and spy. For years Webb has been leaking her politician husband’s government secrets to her spy organisation, The Black Doves. When Webb’s lover Jason is suspiciously murdered, she turns to an old friend, Sam Young (Whishaw) – an assassin whose dark past is swiftly catching up with him.
Set against a backdrop of London in full Christmas swing, the two begin solving the murder, uncovering a web of conspiracies in the process that all lead towards an impending geopolitical crisis.