Sherlock and Kitty are able, fairly quickly, to convince everyone else that Gruner was Kitty’s assailant, but proof isn’t easy to find. Sherlock reasons that someone like Gruner isn’t going to be able to turn his killing instinct on and off, so starts investigating cases of missing-presumed-dead women which might be attributable to Gruner. Meantime, Kitty pretends to have headed back to London, but instead remains in Manhattan to refine her corpse-dissolving technique, lifted from an earlier episode. And Watson confronts Gruner at a charity dinner, after she and Holmes are pointed towards Tabitha Laird, who works for the charity, and who previously made a complaint about Gruner’s conduct. Tabitha will, in an unexpected way, be the key to providing proof one way or the other. But when Gruner goes missing, Sherlock is in no doubt about who has him and why.
Running alongside all of this, though,is what at least one Elementary viewer has been waiting for – flashbacks to the origins of the relationship between Sherlock and Kitty. It becomes clear that Sherlock might have saved Kitty, but she saved him too. Which leads to some of the most emotional moments of the series so far, with the scene in the warehouse, in particular, reaching new heights of intensity: “Whatever you decide, you will always be special to me. You will always be my friend.”
The decision she reaches looks as if it might mean that Kitty has to leave the show, at least as a permanent character. If that’s our farewell to her – and it sure looked like it was – it’s a shame, because Ophelia Lovibond has been a fantastic addition to the core cast. It’s quite a way to go out, though, telling Sherlock that she loves him, and an MVP contribution to an episode which represents another high-water mark for Elementary. I’m not sure it’ll ever be better.