Holmes is engaged in the perfectly normal activity of choking corpses, because he apparently doesn't know that there's already an extensive body of knowledge on the subject of postmortem wounds. But it's okay, because he spots one body that bears evidence of being secretly murdered. After Holmes and Watson barge their way into the hospital room where it happened, they're on the trail!
First, though, they have to find out their victim's name, because the hospital administrator doesn't like Holmes. So they track down a barista named Dave, who was hitting on a perfume saleslady who was the victim's neighbor. Armed with this knowledge, they learn that there was a mysterious doctor who met with the victim at night.
Holmes studies all the medical records in the world, but Watson manages to narrow things down with her expert medical knowledge of how someone might steal epinephrine. This gives them nine victims of what is clearly an Angel of Death, and twenty-three potential suspects. None of them pan out, although they catch one of them stealing morphine. And that one gives them a little bit of information that eventually leads to them deciding that the killer speaks Ukrainian. And that means it was secretly the janitor all along!
Except we're not done yet, because there's still something that bothers Holmes. One of the victims doesn't match up with the Angel's usual plan, and the reason is that the head of surgery made a mistake and covered it up by getting the janitor to murder the evidence. Weird, right?
And while this whole thing is going on, Watson is reconnecting with an old friend. And she's also using her newfound deductive skills to instantly diagnose a case of endocarditis from just some mildly discolored toenails. The show pretends there's some doubt about the diagnosis, but there isn't, really.
Welcome to the episode! Holmes is choking someone! Specifically, a corpse. The morgue attendant is in the same beekeeping chat room as Holmes, so he lets him in. Holmes claims to Watson that the bodies have been donated to science, but if that were true you'd think Holmes wouldn't need to rely on his secret beekeepers' network. Also, I'm surprised we don't have full data on postmortem choking already. It's like on CSI when they're always dragging out dead pigs to shoot. Are they sure no one's already done that test? Holmes calls out Watson as being uncomfortable here because she's a disgraced former surgeon. She won't help him with his important tests. Holmes applies a chokehold on one of the corpses and thanks Bruce the Attendant. Then he notes a body that, according to him, died from a heart attack. Watson explains that there's a blue dot on the head which is a sign of radiation. Further interrogation reveals that this person was in room 704 when he died.
On the way to the room, Holmes tells Watson it was a murder meant to look like an accident. He barges into the room and bullies the janitor out by dumping water out in the hallway. I like the assumption that all the janitor can do is mop the floor and the only way to stop him is to make a messier floor somewhere else. He has a picture of the victim's finger which proves that the epinephrine was administered too late or too early or something. Point is: murder.
As Holmes investigates the room, people pound on the door. It seems like it would be easy to explain himself, but Holmes claims that he doesn't want to interrupt his process. Watson helps him conclude that the killer must have injected the epinephrine into the IV and turned the pump down so the death wouldn't happen while they were still in the room. Holmes is pleased that they have their method already. The people outside say they're breaking the door down and Holmes is pleased that he doesn't need to open it. They come in and Holmes demands to be brought to the Administrator.
After the commercial, Captain Gregson is in the hospital administrator's office, presumably trying to explain Holmes and his ways. Holmes and Watson are loitering in the lobby so Watson can be accosted by an old friend who calls her "Joanie." She's Dr. Carrie Dwyer. Holmes speculates on what could have come between them. Carrie asks if Watson is applying for the spot in cardio-thoracic, since her suspension was for only a few months. Nope! Watson claims to have left medicine behind her.