The narrative begins with the meeting of Dr. John Watson and Sherlock Holmes, who soon take up lodgings together at two hundred and twenty-one B Baker Street. Holmes, an eccentric consulting detective with extraordinary powers of observation and deduction, is soon called upon by Scotland Yard detectives Tobias Gregson and Lestrade to investigate a bizarre murder in an abandoned house off the Brixton Road. The victim is Enoch Drebber, an American from Cleveland, Ohio, who lies dead without any visible wounds, surrounded by blood and the mysterious German word Rache scrawled in blood on the wall.
Holmes quickly deduces the physical characteristics of the killer through meticulous footprints and ash analysis, dismissing the official theories of political conspiracy. While the Scotland Yard inspectors bumble about following false leads, a second murder occurs at a private hotel where Drebber's former secretary, Joseph Stangerson, is stabbed to heart. Holmes utilizes a pair of rare soluble pills and a terrier to prove his theory regarding the method of execution, ultimately setting a trap in his own sitting room to capture the culprit.
Part Two of the novel shifts dramatically to the arid plains of North America in eighteen forty-seven, detailing the arduous trek of a Mormon caravan across the Great Alkali Plain. A dying traveler named John Ferrier and a young girl named Lucy are rescued by the migrating saints and brought to Salt Lake City, where Ferrier prospers as a wealthy farmer. Years later, Lucy grows into a beautiful young woman and falls in love with a rugged prospector named Jefferson Hope, defying the decree of the Mormon elders who demand she marry within the faith.
When Ferrier and Lucy attempt a desperate flight across the mountains to escape forced marriages to the sons of Elders Drebber and Stangerson, they are hunted down by the Danite Band. Ferrier is murdered and buried in a lonely grave, while Lucy is dragged back to the city and forced into a wretched marriage with Drebber, dying of a broken heart within a month. Jefferson Hope, driven by an unyielding desire for retribution, dedicates his life to tracking the two men across continents.
The narrative returns to London, where the dying Jefferson Hope, afflicted by a severe aortic aneurism, confesses his entire story to Watson, Gregson, and Lestrade. He explains how he cornered Drebber and forced him to choose between two pills—one harmless and one deadly—swallowing the other himself, before later killing Stangerson in self-defense. Hope dies peacefully in his jail cell before facing trial, leaving Scotland Yard to take the public credit for the case, while Watson resolves to record the true events of Holmes's brilliant deduction.
