The year is 1896, and St. Paul's magnificent Winter Carnival is under way when Holmes and Watson are summoned by the city's most powerful man, railroad magnate James J. Hill. A wealthy young man disappears on the eve of his wedding—and his fiancée suspiciously discards her wedding dress. After a grisly discovery in the carnival's Ice Palace leads to a flurry of clues, Holmes is on the case.

His pursuit of the murderer takes him through the highest echelons of St. Paul society and into cahoots with Shadwell Rafferty, a gregarious saloonkeeper and part-time private investigator. Soon Holmes, Watson, and Rafferty are embroiled in a perilous adventure that takes them from one frozen corner of the city to another and out onto the treacherous ice of the Mississippi River as they trail a cruel and ruthless killer.