“[A] pitch-perfect murder mystery… If The Crown were crossed with Miss Marple…, the result would probably be something like this charming whodunnit.” – Ruth Ware, author of One by One The first book in a highly original and delightfully clever crime series in which Queen Elizabeth II secretly solves crimes while carrying out her royal duties.
https://www.amazon.com/Windsor-Knot-Novel-SJ-Bennett/dp/0063050005