Joan would like nothing better than to throw away the key. Let Moriarty sit in jail and marinate in her defeat. In her helplessness. In the tattered strands of her once great web.

But Moriarty's web had been wide, and many of her machinations were still in motion even after her downfall. Even then, Joan would rather they ignore Moriarty entirely and solve these cases without feeding her the slightest bit of power. But time is of the essence in this one, and Joan had agreed to go along with this plan on one condition.

She would question Moriarty. Not Sherlock. Sherlock wouldn't even be watching the cameras.

So here she is, in Sing Sing, waiting for the guards to bring the Woman in.