With Princess Mithian as the perfect bait, Morgana conjures a deception so powerful that the whole of Camelot gets taken in - even Merlin himself. As the storm clouds gather, the young warlock must see through the lies to stop Morgana from fulfilling her long-held dreams of revenge.

During a masterclass for talented young musicians held by famous pianist Sir Michael Fielding, prodigy Zoe Stock is shocked to witness a woman drowning in the river, leaving a baby on the bank. However, when police arrive there is no sign of the woman or her child. DCI Tom Barnaby is struck by the similarity of the reported drowning to a mysterious case from 20 years before.

The team re-investigate three murders between 1979 and 1985, when the personal effects of the victims are anonymously sent to one of the widows. What was once thought to be the work of a serial killer is now completely re-evaluated.