The Nonnatus team grow increasingly concerned for the welfare of four young children. Sister Catherine faces her first solo delivery, and the midwives attend a women's lib meeting.
Pine gains Teddy's trust and secretly finds the proof he needs to connect the Cartagena shipment to covert British intelligence interests. But then things start to go wrong.
In a case centered around the fledgling world of psychiatry, a violent psychiatric patient is on the loose, leaving behind a murder, a mystery and an unidentified body. Blake hires Eliza to help him solve the case.