London in the 19th century is a grimy, dirty, dangerous place. Twenty-seven-year-old Sherlock Holmes (Igor Petrenko) meets with Dr. John Watson (Andrei Panin) - a veteran Army doctor who has just returned from the war in Afghanistan. They both live in cramped rented rooms in central London at a boarding house run by Mrs Hudson (Ingeborga Dapkūnaitė). Considering his young detective friend to be a genius, Watson decides to write about the detective's talent, and discloses the mysteries to the whole world in his stories, which often embellish events, based on the cynical advice of a veteran Publisher (Alexander Adabashyan) with a keen sense of what sells.
The real Holmes is an awkward, intense, nerdy younger man. His violin playing sounds terrible, and he is neither a martial arts expert nor a crack shot Dr Watson makes him out to be. In fact, he doesn't even own a gun. Sherlock Holmes smokes cigarettes, but Watson comes up with the idea of the famous pipe for effect. The trademark Sherlock Holmes hat and cape were made up by Watson, as was Holmes' upper-class background. Neither of them is well off.
The two are often invited to take part in investigations by an inspector from Scotland Yard, Inspector Lestrade (Mikhail Boyarsky), whose search for the perpetrator often comes to a standstill. The genius investigator and the Doctor confront extraordinary villains: Professor Moriarty (Alexei Gorbunov), charming Pesutova Baba (Lyanka Gryu), and others.