The Bletchley Circle returns for a second season in 2014. The first episode, Blood on Their Hands opens with former Bletchley Park girl Alice Merren in prison awaiting trial for murder. Jean stands behind her innocence and tries to reunite the circle in an attempt to help one of their own. Lucy is now getting on well in a clerical job at Scotland Yard and keeping her head down, and Millie is working as a German translator. Susan is reluctant to get involved after her experience with the twisted serial killer Malcolm Crowley and the danger it posed to her family.
Next, in Uncustomed Goods, Millie branches out into what she believes to be a harmless sideline of dealing in unaccustomed goods. This endeavor leads to her being kidnapped and held in a seedy hotel by some gangsters. On discovering this, Alice goes to Jean and Lucy to help. The girls start to investigate in order to save their friend and, as they do so, uncover a much darker, hidden world of crime.