Part I of The Violet Hour. It's been months since Moriarty's message. There hasn't been a sign of him since, and Sherlock is looking for a distraction. John and Mary are adapting to parenthood, and Sherlock is desperate to get John out of the house. "The Dancing Men" may be just the case to peak John's interest. SPOILER ALERT for HIS LAST VOW

Sherlock can't turn his mind off, all it wants to do is think about John in a way that he isn't sure he can handle, so he turns to drugs. But when John finds out and Sherlock's past comes back to haunt him will the two be able to navigate the minefield of detoxing, Sherlock's history, and their blossoming love without falling apart at the seams?

When John receives a phone call in the middle of the night, he knows that something has happened to Sherlock, something qualifying as 'not good'. He is, however, not prepared for what has led to his friend's injury and hospitalisation. And he certainly isn't prepared to face the question if Sherlock will ever recover properly from what has happened.