At Rikers, Watson tells Liam he looks terrible. And that is because he's using again. But he needs her help because the cops say he did a hit and run, but he doesn't think he did it. She's skeptical that his total blackout means he couldn't have hit someone. The evidence against him is that there was a picture of his car speeding away, but he thinks he left the keys in his car. So could she just put in a good friend with her friend at the DA's office? Nope. He gets touchy: "You treat all the guys you slept with this nice, or is it just me?" Watson answers, "Just you."
Watson joins Bell and Holmes in Chinatown. Bell is pleased that Watson will deal with Holmes because in the car, he wouldn't shut up about the effect of tides on crimes. Holmes explains that's he's considering writing a monograph, which is exactly the kind of reference to the original stories that I like. Anyway, Holmes and Bell have investigated two gambling parlors and gotten nowhere, so Watson is just in time for the last one. An impassive man with a neck tattoo lets them in. Holmes offers to help with Watson's client. He's clearly jealous that she had another client. She says there's no chance he's innocent.
Bell interrogates a man in English. Watson fills Holmes in on Liam's situation, concluding, "If this is how he bottoms out, I have to let it happen." Bell says no one here speaks English, so it's useless. It's weird that they wouldn't bring an interpreter. Especially after going to two other Chinese gambling dens. Holmes talks to a janitor in bespoke clothes, pointing out that he clearly speaks English and recently applied bleach to one specific part of the floor. The official explanation is that drunk threw up, but there's an awful lot of floor that's been bleached. And those spots on the wall that were recently spackled seem more like the results of stray gunshots than the sort of thing that happen when someone throws up. So Holmes would like to see the footage from the security camera that he says is hidden behind the fake smoke detector. He makes a good point that you don't want to mount a smoke detector above a Hitachi grill. The guy gives up and tells a minion to fetch his computer.
On the video, someone comes in waves a gun around, takes money from Chinese gamblers, and shoots Trent Annunzio at close range. The guy in charge defensively points out that they got robbed too. Holmes says there's got to be another video because the shooter clearly didn't have a mask on at the front door. He runs roughshod over the inevitable objections about how they want to handle it themselves. So the next video shows a great full-face shot of some guy, just before he puts on a ski mask. Holmes: "Detective Bell, I give you Trent Annunzio's murderer."