"Sherlock" season 3 has not premiered in the U.S. yet, but a sneak peek at the season finale has made its way out online following the episode 2 airing on U.K.'s BBC One. The preview introduces Holmes' new enemy Charles Augustus Magnussen, played by Lars Mikkelsen.
"I've dealt with murderers, psychopaths. None of them can turn my stomach like Charles Augustus Magnussen," the title character says of his foe, but his brother Mycroft warns him, "You go against Magnussen, you're going against me."
Magnussen himself seemingly issues a threat against Holmes as saying, "Sherlock Holmes has made one enormous mistake which will destroy the lives of everyone he loves and everything he holds dear."
"His Last Vow", which will air on BBC One January 12, serves as the season 3 finale of "Sherlock". According to the official synopsis, "a case of stolen letters leads Sherlock Holmes into a long conflict with Charles Augustus Magnussen, the Napoleon of blackmail, and the one man he truly hates. But how do you tackle a foe who knows the personal weakness of every person of importance in the Western world?"
The third season of the British crime drama series will premiere in the U.S. Sunday, January 19 at 10 P.M. on PBS.