This book made the WSJ's "Best Mysteries of 2021" list. (I'm slowly getting to the end of that.) Which is kind of odd. Because the book, while good, isn't really a mystery; it's a recounting of the events surrounding the 1566 murder of David Rizzio, which actually happened. Rizzio was the secretary to Mary, Queen of Scots.
It's very short, 118 pages. The author, Denise Mina, has an oddball, but very readable style. She gets into the heads of all involved, and is not shy about speculating beyond the known historical facts. She does a fine job of describing the despicable characters of nearly all involved. She describes the murder as part of a massive conspiracy to replace the Catholic Mary on the throne with her scheming Protestant husband, Lord Darnley. One of the conspiracy's major goals was to force the pregnant Mary to miscarry, via mental and physical abuse. All is described in technicolor, squirm-inducing detail.
When you're as ignorant about sixteenth-century history as I am, the suspense is heightened. I avoided the relevant Wikipedia pages to prevent spoiling that.