Watson's place. Which we've never seen before and will probably never see again. The super is working on her radiator, and they have some awkward banter about it. To be fair, most radiator-based banter is awkward. It turns out that some people on the third floor have a son who was looking at porn on the Internet, and it was made in Watson's apartment. She sublet to a pornographer! Gasp!
Holmes lies on a table in the police station. Watson comes in and doesn't mention it because she's more concerned with her impending eviction. Holmes offers to help her, but she doesn't want to live in that place anymore. She feels violated. Okay, back to the real plot: Holmes has drawn Cassiopeia on the ceiling, with the outline of Manhattan around it. If the first murder is this one star, then Ennis is planning on killing people at these other places, et cetera. He thinks it's a fake code, but he sent the police to the other stars' locations anyway. Also, Holmes admits that he had sex with Drummond when they were working together. Loud, loveless sex. He's very clear on the matter.
Holmes barges into Drummond's meeting with Gregson. He feels that Ennis is going to lay low and change his appearance. The star thing is clearly a red herring. But that's what Drummond said too, so Gregson happily leaves so they can glare at each other. As long as their recommendations are the same, he doesn't care.
At a bodega (that's what a convenience store is called in New York, right?), a blonde woman shops. But who's that guy behind her? He's wearing a hooded sweatshirt and sunglasses, and it's obviously Howard Ennis. He shoots the clerk and the other shoppers, and then asks the blonde to take his picture with her phone. He takes off his hat and sunglasses, and he still looks about the same as he did before. This improves the effect when he holds up a newspaper with his picture.
The cops (and the various consultants) are now there. Gregson is vexed that Ennis shot everyone except the one person who matches his profile. And he didn't change his appearance or lie low at all. So what's the point of having all these consulting detectives and FBI profilers if they're going to be wrong all the time? Drummond admits that it's out of character, but she figures that the register was robbed, which could mean that Ennis he just needed money. Holmes says he picked a low-cash place, and also that her theory doesn't explain the woman he didn't kill.