After pursuing her cousin Alice's ends through several novels set in London, Dame Frevisse is once again where a Benedictine nun belongs, at St. Frideswide's. Part of her vows included "stability," the idea that the nun belongs for her lifetime in a particular "house" or convent. All Frevisse has ever wanted is to pursue her relationship with God: the novels all consist of interruptions to this peaceful search. The Apostate's Tale both fits this formula, and turns it on its head.
Sister Cecilia, whose family had pressed her to a vocation she did not feel, fled St. Frideswide's in a previous novel. Now the apostate nun has returned, with her son, after the death of her lover of ten years. Modern sensibility immediately sympathizes with Cecilia; Frevisse, with the appropriate fifteenth century attitudes, does not. Lifetime commitments remain constant, although the people who made them may change. The tension here is between stability and mutability, a most appropriate conflict for Frevisse.
Of course there is a murder, of course Frevisse must make difficult decisions, and the reader will enjoy not only Dame Frevisse's detective skills but her personal growth in this, the best of Frazer's excellent novels for several years.