On this fresh and modern take of Sherlock Holmes, the greatest detective in the world relocates to New York City after getting out of rehab. His new sober companion is Joan Watson, a former surgeon. Together, they make an unlikely pair who solve unusual and difficult crimes at the behest of the New York Police Department.
Sherlock takes Joan under his wing and begins teaching her how to solve crimes and how to see what others missed. Her medical background comes in handy as they investigate murderers of great cunning, including Sherlock's arch nemesis, Moriarty.
Along the way, Sherlock helps Joan regain a sense of purpose she lost when she gave up her scrubs after a mistake cost a patient his life. Joan helps Sherlock care about someone again since he has trouble letting people get close to him after losing someone he loved.
While trying to uncover who Moriarty is, Sherlock stumbles upon his lost love, Irene Adler. Later, he discovers that Irene is actually Moriarty. He wins their duel of the minds, but doesn't come out unscathed. Later his brother, Mycroft, reappears in Sherlock's life, much to his displeasure. Mycroft and Joan hit it off, but Sherlock is certain that his shady brother is hiding something and he is. He's MI6, British Intelligence.
While Joan and Sherlock continue to solve crimes together, their partnership is entering a new phase as Joan moves out.