Feef is tasked with rooting out Soviet moles who have allegedly infiltrated the new Labour government under Clement Attlee.

The series concludes on a bleak note, showing the personal and moral cost of espionage as Feef is forced to make impossible choices "for England" that leave her isolated and hollow.

She is caught between her duty to her country and her role as an American operative, supervised by the zealous American handler Thomas Rowe .