Sherlock Holmes and Dr. Watson are summoned to the aid of Queen Victoria in Scotland by a telegram from Holmes' brother, Mycroft, a royal advisor. Rushed northward on a royal train—and nearly murdered themselves en route—the pair are soon joined by Mycroft, and learn of the brutal killings of two of the Queen's servants, a renowned architect and his foreman, both of whom had been working on the renovation of the famous and forbidding Royal Palace of Holyrood, in Edinburgh. Mycroft has enlisted his brother to help solve the murders that may be key elements of a much more elaborate and pernicious plot on the Queen's life. But the circumstances of the two victims' deaths also call to Holmes' mind the terrible murder—in Holyrood—of "The Italian Secretary," David Rizzio.