‘The Illustrious Client’ – named after, and occasionally borrowing from, an Arthur Conan Doyle story – is driven by the development at the end of last week’s episode: Kitty’s abductor/rapist is in town, and Sherlock doesn’t think it can be a coincidence. Chief suspect Simon DeMerville – also involved with a brothel which uses trafficked sex workers – goes on the run, possibly going to his sister Violet for assistance, but she can’t or won’t help. So Kitty decides to persuade her. We’ve seen before that Kitty has a dark side, of course, ruthless and perhaps dangerous, and it’s chills-down-the-spine time when Violet goes back to the police having revised her position.
DeMerville is found dead, which seems to close the case, but for an audience well versed in the conventions of procedurals it’s all seemed a bit too quick, a bit too easy. Everyone is convinced that DeMerville was Kitty’s attacker, and that she isn’t in danger any more, but she knows better. But if it wasn’t him, who was it? The moment of revelation requires some top-notch acting from Ophelia Lovibond, and she certainly sells the moment; it’s as disturbing a scene as Elementary has given us so far. Even by the standards of this season, a startlingly and thrillingly good episode.