Italian secretary

The quiet comfort of the living room on Baker Street, 221b is again broken: Sherlock Holmes receives a encrypted message from Microft"s brother. Queen is in danger! Under mysterious circumstances, two of her close circle have already died ...
The greatest of the detectives and his friend and assistant Dr. Watson immediately go to the Scottish castle of Holirud, whose stones were once stained with the blood of the victim of the murder. Three centuries ago, on the orders of the spouse of Queen Maria Stuart, her court secretary and musician David Ritzio was stabbed here.
"Affairs of past days"? Or maybe there is a connection between these crimes? Be that as it may, Sherlock Holmes, using his deductive method, intends to understand everything and find a fierce killer