Holmes has an unexpected visitor: Rhys, his old drug dealer! It's always nice to meet up with old friends, isn't it? Rhys isn't here to sell drugs; he's here because his daughter Emily has been kidnapped. This is probably his fault, because he once stole 2.2 million dollars from the Dominican cartel. Nice going, Rhys.
The first place Holmes checks is Emily's house, where she was abducted. A barrage of Holmes-style deduction (and cigarette-ash-identification) leads him to the conclusion that she was abducted by someone who'd recently been at a Brooklyn nightclub named "Hurricane." But when they get there, Holmes finds an undercover DEA agent who beats him up while promising him that the cartel has nothing to do with it.
The kidnappers raise the stakes by sending Holmes one of Emily's fingers. This lets Holmes determine that she's being held in a prewar building (because of a radiator burn) near an Ethiopian restaurant (because he tasted the gunk under her fingernails, which is gross). But that doesn't get him there, so he has to borrow 2.2 million dollars from his father to pay the ransom. Along the way, Rhys tries to give him cocaine, but he bravely turns it down. Good for him!
The handover of the ransom is interrupted by a Dominican hit squad. And it's Agent Diaz of the DEA who was behind it, which we know because he shows up at the Brownstone with a gun. Luckily, Rhys frees himself and Watson before getting shot. Then Watson takes the bad guy out with a well-placed phrenology bust. After some interrogation, Diaz confesses to Gregson and Bell, which means he's still going to jail but won't get murdered right away. Holmes gives Rhys some money to stay on the lam, then he makes a huge breakthrough by deciding to go to a recovery meeting and actually talk about his struggles with addiction. Instead of just reciting the plots of old Arthur Conan Doyle stories like he was doing at the beginning of the episode.
A woman enters her house, apparently after going for a run. I deduced that from the running clothes she's wearing! And from the water she's drinking. A man knocks on the door and asks to use her phone because he needs to deliver some tables and chairs. He's got a cellphone and he needs to charge it up. She won't do it. She offers to call for him, but he can't remember the number. Disgusted, he leaves. And then she's grabbed by someone inside the house! He appears to use chloroform. Then he unzips a large rolling suitcase next to her unconscious body.
Outside, the delivery man thanks a cab driver for letting him charge his cellphone. In the background, a man pulling a large rolling suitcase goes past. In voiceover (that changes to in-person), Holmes explains that a man dropped his walking stick to pick up a mongoose. The man was a magician and this is all terribly elaborate. He's showing off for his recovery group. He ends with, "Again, my name is Sherlock and I'm an addict."
The story Holmes was telling is "The Adventure of the Crooked Man," the Arthur Conan Doyle story where Sherlock Holmes comes closest to saying, "Elementary, my dear Watson." Actually, he only says "Elementary," but he does say it to Watson. I approve of the occasional nods to Doyle.
Holmes and Watson come home, and Watson complains that Holmes is supposed to talk about his addiction, not his ridiculous life story. As Watson enters her home, a naked man comes out of the shower. Holmes comes up and calls him "Rhys." Rhys says that Emily has been kidnapped, and they got a ransom demand via video. Watson requests that Rhys put on some clothes, but she's a little put out when he enters her bedroom to do it. Holmes fills in the backstory: Emily is Rhys's daughter, and Rhys is Holmes's former drug dealer.
In the kitchen, Holmes makes tea. He also tells Watson that Rhys stayed in Watson's room. And he's an ex-dealer. Watson busts out the title of the episode, calling him "a giant gun filled with drugs, pointed at you." If that weren't the real title of the episode, I'd totally make it my fake one. Rhys comes down, and Holmes tells him he's sober and that Watson is here to keep him that way. Rhys accepts this.