Katherine Corven awaiting execution for murdering her husband is reprieved on the confession of her housekeeper. Father Brown is afraid she will take revenge on his friends. A wardress from Corven's prison is found hanged in a locked cottage and Corvens alibi is provided by the mother superior where she is training as nun. A local reporter pursues Father Brown and accuses him in the press of impropriety with Corven. Bunty goes missing and Father Brown is expected to confirm the story or Bunty will die. A Jackdaw flying in the church gives Father Brown the clue to the death of the wardress.