A friend was planning to give it away and asked it I wanted it. I said sure, figuring I can always donate it to a library later if I don't want to keep it. As it stands, I don't think I've read anything of Carr's since The Alienist, which my dad gave to me back in the misty days of junior high. I can't tell you if I enjoyed that book or not, since I probably read it grudgingly, as that was my default response to pretty much anything my parents offered or requested at that time.
In this case, Carr has eschewed stories set during Teddy Roosevelt's tenure as New York City police commissioner in favor on a Sherlock Holmes tale. Mycroft Holmes requests Sherlock and Watson travel to Scotland, where two men involved in the upcoming renovation of the west tower of Holyroode - where Mary, Queen of Scot often stayed until a man named Rizzio, the Italian secretary in question, was murdered by people who didn't want Mary hanging about any dadgumed Catholics - have been found dead, stabbed many, many times. Holmes confounds Watson by not immediately dismissing the notion that the ghost of Rizzio has something to do with it all. I will admit I was also confounded because having Holmes admit the possibility of the supernatural seemed as out of place as having Scooby-Doo contend with real werewolves and ghosts of space aliens, rather than cantankerous people in goofy costumes.
As it turns out, and as Holmes explains near the end, he meant something different than Watson (and I) thought, but Carr still seems to hint at there being a spirit running around the house, and that it was getting involved in the whole mess for some reason. I've no idea why it would get involved, nor does the book offer an explanation, though horror movies have taught me the best explanation is, "ghosts are jerks". Stop bothering innocent living people, innocent dead people!
The story breezes by; I read it in an afternoon, and it didn't seem to cover more than two or three days. Holmes seemed to know basically what was going on by the time they reached the castle, and put the remaining pieces together by that evening. It wasn't a terribly difficult mystery, seeing as I had most of it figured out before the end. I did make a mistake on how they shattered the bones of one of the victims, but on the whole, things were straightforward. I wouldn't consider it essential reading for a Holmes fan or, a fan of mysteries in general.