The Tavern in the Morning (Hawkenlye Mystery Trilogy)

At the end of a dark and dreary market day, Goody Anne's inn at Tonbridge is finally settling down for the night. But while Anne's serving maid and boy finish up their chores, a man lies dying in the guest chamber-poisoned by a piece of pie made by Goody Anne herself.

Josse d'Acquin, a knight with a knack for solving mysteries, is troubled by the news of the stranger's death. Josse has been a regular visitor to Goody Anne's, and he hates to think that Anne-or her fine cooking-has fallen suspect. He rides off to the scene of the crime and starts his own investigation.
When Josse discovers wolf's bane in the remnants of the pie, he knows that someone must have tampered with Anne's cooking. And when he learns that a charming, handsome nobleman ordered a piece of that very pie, Josse is convinced that the poison was meant for this upper-class guest, and not for the poor stranger who died alone in Anne's guest chamber.
After failing to persuade the Sheriff that the death was suspicious, Josse turns to his old friend, the formidable Abbess Helewise. Weakened from a severe bout of fever, the Abbess nonetheless provides a thread of common sense as Josse follows the trail of murder into the ancient, mysterious Wealden Forest, and finds something there that will change his life forever . . . .