Sherlock’s new adversary has been revealed! The villain in His Last Vow (the final episode of Sherlock series 3 written by Steven Moffat) will be Charles Augustus Magnussen. Magnussen is being played by Lars Mikkelsen best known as mayoral candidate Troels Hartmann from Danish series The Killing. Lars is the older brother of Mads Mikkelsen (currently playing Hannibal Lecter in the tv series Hannibal)
Charles Augustus Magnussen is possibly Sherlock’s take on Charles Augustus Milverton who appears in the Conan Doyle short story The Adventure of Charles Augustus Milverton. In the story Milverton is described as the “king of all blackmailers”.
His Last Vow started filming on 29th July.