Life on the estate of the ka-priest Imhotep doesn't seem to have changed at all in the eight years of Renisenb's marriage; returning to her father's house upon her husband's death, its stability comforts her, even though it isn't entirely peaceful. But how much of the impression of changelessness is wishful thinking?
Her eldest brother, Yahmose, gentle, conscientious, reliable, is still henpecked by his strident wife Satipy, urging him to demand that Imhotep create a legal agreement giving Yahmose formal administrative status. The middle brother, Sobek, is a womanizer given to high living, who fancies himself a great man; his wife, Kait, may seem solid and stupid, but she's devoted to her children, and won't let him abandon their heritage however piqued he is with his father. Young Ipy, at sixteen, is no longer a pretty sight after being spoiled for so long.
Then middle-aged Imhotep returns from a trip to Memphis and puts a cat among the pigeons: he introduces his new 19-year-old concubine, Nofret. She's unhappy at being tied to this fussy old tyrant on his backwater estate, after Memphis, but works to ensnare his affection - and facing the family's hostile reaction (except the amusement of Imhotep's aged mother, Esa), begins undermining them with him. (Christie gradually, skillfully illuminates Nofret's character; she's no cardboard evil temptress, and not really evil at all.)
During another of Imhotep's trips, the cold war between Satipy, Kait, and Nofret comes to a head when Kait slaps Nofret - who then reports the truth and nothing but the truth in a letter to Imhotep, supported by testimony from the staff. Imhotep's reply falls like a boulder into a pool: Yahmose and Sobek are to be disinherited, while Imhotep will marry his concubine. But soon after the message arrives, Nofret is found dead, fallen from the cliff path near the tomb (the entire estate is an endowment, supporting the family in exchange for their maintenance of the tomb, hence Imhotep's job description as a ka-priest).
This isn't a group of modern people set in an Egyptian background; the different culture is apparent. (Christie's 2nd husband, of course, was the archeologist Max Mallowan). The family (regardless of their suspicions) is content for this first death to pass as an accident, but as the death toll rises, some attribute it to Nofret's angry ghost while others, including Renisenb, wise old grandmother Esa, and the steward, Hori, look for a more immediate agent. (I believe I counted 8 deaths - I won't say if they were all murders - through the course of the book.)
A novel in ancient Egypt, when well written, is always a pleasure, and Christie (particularly when not hogtied by formulae required by some of her more famous characters) is of course great at designing puzzles with human touches. The combination here is very good.