Holmes and Watson enter the lab and find Kademan dead. For the record, I typed that before it happened. I'm a WIZARD! Either that or her death was pretty obvious.
Bell says it looks like someone's burglary was interrupted. Holmes disagrees, because that expensive portrait wasn't stolen. He thinks it's related to the Lydon case. Gregson says the Lydon case is closed. Holmes brings them up to speed, because no one else knows about this theory that he'd been infected with a hereditary disease. Holmes says Kademan made someone nervous enough to stab her. And the killer's blood is on the portrait. Why is that the killer's blood? Watson is put on the spot to explain: The blood on the floor suggests that she was facing away from the portrait. Holmes barely praises her, "Kudos, Watson. Adequately done." Kademan's fiancé comes in. He's also a geneticist and he thought they were going to ask him about Benny Cordero, who was one of the subjects for the Warrior Gene study. He was in jail for stabbing someone and recently got out.
Sitting on the floor of the brownstone, Holmes makes a model of the molecule that was sent to them in that text. The elements aren't labeled on the diagram, so he's really just playing with expensive tinker toys. Watson points out that they have a list of brilliant geneticists he could ask, but those are the suspects. So he doesn't want to go to them.
The next morning, Watson disassembles a dinosaur that Holmes had apparently constructed. She also has the correct molecule, because she emailed her old genetics prof. It's a man-made chemical, which is a mutagen. The next question is whether they prove that someone paid a genius to create it. Holmes stands weirdly and gets Watson to go pick up his dry cleaning. Swerve!
At the cleaners, Watson is ignored by the woman behind the counter, who speaks a foreign language and is watching television. Everything she says is translated into English by a bald guy wearing sunglasses. Watson notes a fur coat, then gets a text to meet at the police station. The woman claims the bill is $75, then drops it to $19. Watson asks for a receipt, but one is not forthcoming. That was odd,
At the police station, Benny is being interrogated by Gregson and Bell. He's mad about being called an incurable sociopath in Kademan's original paper. Also he denies killing her. From behind the interrogation mirror, Holmes says Benny is a blackmailer and a blackguard, but he's innocent. Bell tells Benny that they have his DNA on file since he's a felon. Then he and Gregson get texts saying "Sociopath but not killer" and "Innocent!" Then Holmes bangs on the mirror when they won't stop interrogating him. He insists that this crime is too elegant for this guy to do it. Bell still wants to run the DNA and Gregson mocks Holmes's theory. Holmes is off to prove the validity his crazy ideas.