"To Sherlock Holmes, she was simply known as The Woman." Is that loathing, or a salute? Who is this Woman you ask? Irene Adler is her name.
In A Scandal in Belgravia (based off of the Arthur Conan Doyle story A Scandal in Bohemia,) Sherlock Holmes encounters love in the form of a mysterious woman; A dominatrix. Now in the books, she's from New York, and she has a very....compromising photograph of an ambassador. In this version she has one of the queen-to-be, Kate Middleton. Sherlock has been called to take back the photograph. As it turns out, the picture is on Irene Adler (The Woman)'s phone. Her life is on that phone; passcodes, documents, things that can make the British Government crumble overnight. Obviously, this draws the attention of a certain Consulting Criminal (Jim Moriarty) which in turn leaves Mycroft's hands tied. He's trying to help the government get rid of a terrorist bomb that would take out a whole airplane full of people. In the end, it's not successful. Irene tricks Sherlock into deciphering the code and thus letting Jim know about the bomb.

The way that they portray Irene as a Dominatrix brings a new prospect on the old story. It gives Sherlock a chance at love, which John thinks Sherlock is uncapapble of feeling.

There are lovely moments in this between our two flat mates, especially a scene in Buckingham Palace involving a sheet. That's all I'm going to say on that matter.

Lara Pulver plays Irene amazingly. She brings a darker side to Irene than Rachel McAdams (who plays Irene in the Guy Ritchie movies) does.

I highly recommend the watch. As in the other season of the show, the first and the last episodes are the best.

If you need me, I'll be over in my corner with a smiley face on the wall wrapped in a shock blanket.