Sherlock does not dream - not normally. Such indolent and uncontrolled thinking is a waste of time, when a mind like his can be occupied studying the libraries and organizational wonders of his mind palace. He learned to control his dreams long ago, to use them productively, to rid himself of the moments when his mind was not his to control - lucid dreaming, they called it, but for him was regarded as a simple extension of his consciousness, a place for him to continue his deliberations and deductions in peace.

Tonight, however. Tonight is not a night for lucid thought.

Tonight Sherlock's mind palace is full of unopened doors. It intrigues him, the mystery - he has always known his mind palace, every room, every crevice. He cannot help his curiosity - what are they? Where do they lead? He certainly didn't put them there, so who did? He must know. He has no mysteries; he has solved all of his personal dilemmas ages ago. He begins to open them, because he has to, because he is Sherlock Holmes and nothing, nothing is a mystery to him.

Behind them he finds things he confusion. Things he dislikes, things he cares nothing for, things that challenge even his mind. Many do not, he observes, deserve a place in his palace on their own, but their collective presence and the lack of reason behind them is a case he cannot ignore. He delves deeper, and soon there are whole hallways, labyrinthine wings to the palace that were never there before, filled with images and memories and wonders from beyond his time.

Sherlock knows it is beyond the scope of his current knowledge, so he does the only thing he can do - he wakes up, and begins the hunt for clues.