The Canterbury Papers by Judith Koll Healey is the first book of the Alais Capet mystery series set in 1200 France and England.
Historical facts revealed during the action of the story: Princess Alais Capet, daughter of King Louis VII of France, was raised in England by her stepmother Queen Eleanor, former wife of King Louis, later wife of King Henry II. Alais was once betrothed to Eleanor and Henry's son Richard (The Lion Heart). Her childhood dreams were forever disrupted when Henry imprisoned Eleanor.
Decades later, Alais lives in the Paris court with her brother, King of France. She's resigned to a life with little interest or joy. All she has left from her past is a treasured jewel pendant from Richard, that she wears always. Alais receives a message from Eleanor (after all the years of estrangement), asking her to undertake a secret mission to England. Eleanor wants Alais to retrieve letters written by Eleanor to Thomas Becket, hidden at Becket's altar in Canterbury Cathedral. The letters pose a risk to her son John, King of England, who is fighting with the Templar Knights for control of abbey revenue. In return for the letters, Eleanor promises to reveal a secret that Alais desperately wants to know.
Wild adventure ensues! In a fast-paced and entertaining sequence of plot twists, Alais is drugged, captured, robbed, threatened, rescued, romanced. Hard to identify the 'good guys' vs. the 'bad guys'. Through it all, Alais shows great spunk. She never stops demanding answers, until she finally learns what really happened in her past. The book's ending promises more adventures to come.
Sending Alais to recover hidden letters strikes me as an implausible plot device. A visit to England by a royal princess from France, and her actions during the visit, will be noticed by many; in contrast, an English servant loyal to Eleanor could obtain them unobtrusively. It seemed obvious that Eleanor intended all along for Alais to be captured, so that Alais would have access to Eleanor's writing desk in Sarum Tower. But Eleanor didn't confirm that in the end - odd.