Previously on Elementary: We Are Everyone.

As a mysterious, latex-covered case continues to mystify Sherlock and Joan, so does the reappearance of someone from his past.

When he was just 15 years old, Sherlock became interested in the case of Abigail Spencer, a young woman accused of having murdered her father. Being the victim of merciless bullying at the boarding school his father had shipped him off to — and in those days, that didn’t mean nasty facebook entries, it meant frequent beatings and violent hazing — Sherlock was desperately searching for something to hold onto, for something to do. Having always been interested in murder and the criminal mind, he chose Abigail as the subject of his experiment. He writes her a letter, promising to keep her confidence — those are the beginnings of one of the stranger pen pal stories. It’s a mark of who this Sherlock Holmes is that he continues to underestimate his own emotional reactions.

He wasn’t going to like living with Joan, wasn’t going to want her to never leave. He wasn’t going to fall in love with Irene, wasn’t going to nearly destroy himself for love. He wasn’t going to feel so incredibly fond of Abigail — for showing him a purpose, for unknowingly and unwittingly sparking within him the wish to become a consulting detective. He wasn’t going to put his ego aside so firmly that he didn’t jump up and down telling everyone about solving his very first case. (That’s very funny wording, by the way: “She was your first.” First love, first case, first murderess — with Sherlock, that’s hard to tell apart.)

Their correspondence got both Sherlock and Abigail through terrible times, and their bond was real. They could have become good friends if Abigail hadn’t decided to finally give in and serve a sentence for a murder, though not the one she did actually commit. Sherlock feels responsible — for driving Abigail to this by confronting her with his knowledge of her guilt, and for failing to convince her to retract her confession. He then tries to make amends by both warning Graham to keep on the straight and narrow and heed the sacrifice that Abigail has made for him, and offering him help, someone to talk to. He might not advertise it, but Sherlock is a big fan of decency.

This episode was another big win in term’s of Joan’s apprenticeship. She’s steadily honing her skills; and although she’s always had a remarkably good Sherlock’s Lying to Me radar, she’s now even better at reading the master of deduction himself. Although it’s slightly annoying that she keeps categorising any relationship he has with a woman as potentially romantic — writers, Joan is one half of a platonic partnership that is brilliantly written and that you producers have made it a point to keep platonic at all times, why do you let her keep automatically assuming that Sherlock fell in love with every woman he ever had a meaningful connection with? Sure, him having meaningful connections with anyone is basically a red flag, but she never once assumed he was in love with her.

Next: Ancient History.