I found this a very interesting plot. The means of murder was quite clever, and, for its time, must have been quite extraordinary. I was saddened at the loss of Dame Frevisse's uncle and dearest friend, but we're introduced to her cousin Alice, who becomes a strong recurring character in later works. Not to mention the bishop, who, despite also being a good friend of Thomas Chaucer, and a very clever, insightful man, just somehow irritates Frevisse, although she is properly obedient to his wishes.
However, there was a minor side point at the beginning of the story that so startled me (not to mention the two nuns it affected) that I found my thoughts returning to it again and again. At the end of the previous book, Frevisse was left feeling guilty for not having prevented one of the deaths that occurred. To my mind, she's taking on too much. She hadn't seen the person in question for sixteen years, and couldn't have known how he would react to the situation. Anyway, Domina Edith names her as sacrist in order to give her more time in the church to pray and reflect. That's fine. Perhaps to cover any idea of favoritism, or perhaps simply because it was time, she also changes around the other offices that the nuns hold--such as pulling Dame Alyce from her tyrannical position as cellarer. (BTW, for a long time I thought Alyce was simply a servant, with the courtesy title of "Dame" because of her obnoxious attitudes. I was surprised to realize that she was also a nun!) This is also a good idea. It keeps the nuns from falling into a rut, and helps them develop other skills. HOWEVER...Domina Edith also pulled Dame Clare from her position as infirmarian and installed Sister Thomasina in her place. This was utterly absurd. What was she thinking? What was Margaret Frazer thinking? An infirmarian might not be an accredited physician, but it was the closest thing they had to it. Think about all such a person would have to know: a knowledge of illnesses and how to treat them, knowledge of wounds ditto. Knowledge of herb lore: which herbs are good for what, how to grow them, how to harvest them, how to preserve them, how to distill them into balms, salves, tinctures, and so on, and so on. And Domina Edith proposed to throw the youngest, least experienced nun into this position? "Oh, you'll pick it up in a week or two!" No doubt poor Thomasina was left constantly rushing to consult with Clare. I'm wondering how many people wrote to point out this absurdity to Frazer, because I noticed that about two books later, Dame Clare was quietly reinstalled in her place. Still later, one of the newer nuns, Johane (?) appears to have become an apprentice of sorts, which is the intelligent way to go about it, because sooner or later they're going to need a new (and properly trained) infirmarian.