Two years of wait and it is already time to talk about the final episode of "Sherlock" Season 3. The third episode is "His Last Vow," and according to the spoilers, this episode is likely to be drenched in tears.

'Sherlock' Season 3 began on a note of Sherlock coming back to London, and revealing to everyone that he is not dead. He finds that Watson has moved on and is in a serious relationship. Sherlock didn't get a friendly, welcome back hug from Watson, but instead he received plenty of punches. However, the two friends had their proper reunion while stopping a terrorist attack, which aimed to blow-up the House of Parliament. At the end of episode 1, "The Empty Hearse," there was a fleeting glimpse of this season's nemesis.

In episode 2, "The Sign of Three," Sherlock gave a heart-warming, best-man speech, which did have an erratic beginning. He expressed in words that he loved his best-friend and that he will always be there for Watson, Mary and their child. In the episode that aired on Sunday, he solved a murder mystery and saved a man's life. At the end of the episode, Sherlock walked out all alone, while the rest happily danced in the wedding hall. The scene underlined a new beginning for Sherlock, Watson and Mary.

[Youtube/BBC]

The episode 3, "His Last Vow," will introduce Charles Augustus Magnussen. The one man Sherlock hates. He is chillingly terrifying and is called the "Napoleon of blackmail." In the preview video of "His Last Vow, one can hear Sherlock express his hatred for Charles Augustus Magnussen. The trailer clip also provides a proper glimpse of the new adversary in Sherlock's life. The new villain believes in destroying everything that Sherlock aims to protect.

In the trailer video, Mycroft can be seen telling Sherlock that if he goes against Magnussen, he will find himself going against him. Also, Magnussen can be seen coldly threatening that a mistake can destroy the lives of everyone that Sherlock loves.

BBC's Official Synopsis of "His Last Vow":

"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?"