Interrogation room. Gottlieb explains, "I just bred an antibiotic-resistant strain of rubella." Well, that sounds perfectly simple. Gregson says he's given up 18 murders so far and doesn't want an attorney. Holmes thinks he's probably just happy to have an audience, since he's been anonymous this whole time. Gottlieb's phone (in Gregson's hand) gets an encoded text, so Holmes goes in to talk to him. Gottlieb says he can't read it because, "That's not the code we used." He thinks Holmes will have to translate it himself.
Holmes goes to Newgate Prison to talk to Moran again. Holmes says John Douglas in the morgue. Moran seems to think Holmes has done good work. Holmes asks for a translation of the text, and Moran mocks him for not doing it himself. He directs Holmes to the incoming text log. Now back to the message. Long, long pause. He says it's not the code they used to use and Holmes says he's lying. As Moran is being led away, Holmes pleads, "Tell me what it says." Moran tells him, "Leave it."
Holmes works on the code. Watson comes in and observes that he hasn't been sleeping. Holmes says he's figured out the theoretical underpinnings of the code, so now he just needs a three-digit sequence. Watson says its 10:17, so he has until 11:00, and if he doesn't have it by then, he'll have to go to sleep. Holmes gets Epiphany Face: "Watson, you know, some people without possessing genius have a remarkable knack for stimulating it." Watson is impressed: "An insult and a boast." Holmes says Moran wanted to look at the list of incoming texts because he was looking at the time the text was sent: 4:32. And then he deciphered the message in his head? Neat.
In his cell, Moran sings My Bonnie again. Except it has Arsenal lyrics, like "Bring back the champions to me" and "Bring back the Arsenal to me." He gets up. Now he starts another Arsenal song, which I take to be the standard Arsenal fight song. Holmes translates the code back at the Brownstone: "Moran, you never told me you had a sister. She dies or you do. Your choice. M." Hmm. Holmes grabs the phone as Moran headbutts the mirror in his cell. Holmes tells Gregson that Moran is going to commit suicide. Too late. He was still alive five minutes ago, but his brain is swelling and he won't last the night.
Watson observes that Moriarty had Holmes bring the message to Moran, and that's twice Moriarty has outsmarted him. She observes, "It seems like maybe you're the game." I'm certain he has figured that out on his own, Watson. You're kind of piling on. Gottlieb's phone rings. Holmes answers while Watson records on her own phone. It's Moriarty, and he believes he and Holmes are overdue for a chat. Here comes the end of the season!