Little Walsingham has always been famous for religious visions, so when Cathbad, now living with Judy, sees a vision of the Virgin Mary, no one is too shocked. But then a woman dressed in a blue cloak is found dead, and people begin to see the apparition in a different light. The woman is identified as a patient in a local psychiatric hospital. DCI Nelson investigates and finds that staff and patients in the small, privately run hospital seem reluctant to speak to him.