What a fun story! Queen Elizabeth II as a sleuth (discreetly, of course) is a wonderful premise.

The Queen is at Windsor Castle ahead of her 90th birthday celebrations and she is not happy. A guest has died in one of the castle bedrooms and the Queen wants to get to the bottom of the case.
She ever-so-gently guides the professional investigators in the right direction so they can solve the mystery. In the process, she shows herself to be kind, curious, and a shrewd judge of character.
I am so looking forward to the next book in the series!
Read more about The Windsor Knot on Goodreads.