A man suspected of being a multiple murderer is killed in prison while on remand awaiting trial, leaving the disappearance of a fifth woman unsolved. 
In the missing woman's effects was a postcard of a pre-Raphaelite painting, the background of which was painted in some woods near Oxford. Morse is assigned to a new murder investigation when what appears to be her body is found in the woods.

A young woman is shot dead through her kitchen window one morning, and an anonymous valentine seems to be a clue to the killer's identity. Morse interviews the neighbours, including Geoffrey Owens, an aggressive journalist, and Adele Cecil, a music teacher - he is very taken with Adele and hopes she has nothing to do with the killing. Then, at the same time of day the next morning, Geoffrey Owens is also shot and killed, and Morse and Lewis deduce that the two murders are connected to a bitterly fought contest taking place at Lonsdale College, Oxford. The current Master of Lonsdale, the malicious Sir Clixby Bream, is retiring, and two of his dons, Denis Cornford and Julian Storrs, are vying for the Master's job, with their wives active behind the scenes.