Faith Alexander arrives in Midsomer Deverell to meet her long-lost uncle Rex Masters. But Rex has told everyone that Faith's entire family was wiped out in a plane crash - and he has disappeared.

Thanks to Miles King, an old friend who does Rex's gardening, news spreads quickly. Rex's cook Eileen Carnack, cleaner Janet Bailey and Janet's fiancé Jeremy Thacker rush to his home, Stonecroft House. Faith is anxious and can't understand how Rex has photographs of her when they haven't met following a 40-year family feud.

Barnaby asks Jones to investigate the disappearance. Faith explains the feud had something to do with her mother's childhood friend Lucinda Thacker, who went on to become the famous missionary Mama Lucy of Ethiopia. Janet is shocked - Lucinda was Jeremy's mother and he is devoted curator of the Mama Lucy Museum.

Rex's body is found in the river, below Crofter's Weir. Bullard suspects he was hit before he entered the water. Faith decides to stay on at the house, befriending Janet.

Solicitor Jane Benbow has a will showing Faith is the main beneficiary. But then Eileen, Janet and Miles all produce new wills, stating each of them will inherit Rex's wealth. Janet's is the most recent, and Miles and Eileen realise they have been tricked into years of unpaid work by their mischief-making friend.

An intruder tries to break into Rex's study in the night. Barnaby reads Jeremy's biography of his mother and suspects the family feud started because Rex sexually abused Lucinda when she was a teenager.

Meanwhile, Mrs Benbow discovers Rex was making substantial payments to Faith's husband Alan. He arrives and is arrested. Alan admits gaining £160,000 from Rex and sending him family photos. But he claims he is not the killer and witnessed someone else break into Rex's house the night he vanished. Then Barnaby and Jones find the bodies of Miles and Eileen, brutally stabbed to death.

Barnaby returns to Rex's study and finds some important clues in his erotic photographs from the 60s. Can he get to the bottom of the tangled relationships stretching across the generations and identify the killer?