While 'His Last Vow' is a study of the mind that is Sherlock Holmes, 'A Scandal in Belgravia' is study of his heart. From the hugely funny - "Are you wearing any pants?" - to the strangely deep - "All hearts are broken; caring is not an advantage" - 'A Scandal in Belgravia' isn't just an episode of television, it's a journey; it tracks a relationship, from the spiky beginnings of her appalling him with her attention-grabbing nudity, to the silent affection he has for her by the end. Lara Pulver is masterful as Adler, Cumberbatch delivers a very different side to Sherlock, and the mystery, the big mystery of the episode, is what could possibly unlock Irene's heart. The reveal that it is in fact "I Am Sherlocked" might seem obvious now, but the ingenuity of building this invisible love affair, before exposing it with a pin code, is deftly judged and wonderfully paced. Pulver and Cumberbatch have a friction early on that melts into sumptuous chemistry: the couple are two sides of the same complex coin, and the fact that you can never second-guess either of them - and they can't second-guess each other - only makes for more interesting watching. Because they're, effectively, a pair of people who don't understand each other. Sherlock doesn't feel love like she does, and she longs to see inside his head. It's fitting really that she lives in his mind palace.
