The Castillos want to make the trade. But the police can't do that. The Castillos don't believe that Adam is just "a victim". They're jerks about this, in my opinion. Holmes points out that victims of horrific abuse are often protective of their abusers, but that doesn't mean they should be sent back there. Holmes wants to go back to the files. Gregson says no cop can talk to Adam. No... COP. Before acting on this semi-legal plan, Holmes takes a moment to tell Watson he might even listen to her again in the future. But "not your sobriety twaddle." She hasn't really done much sobriety twaddle.
Holmes goes in and talks to Adam, who considers Samuel Abbott his dad. Adam admits that he helped "take the others". He says he's confused. Adam asks if he signs the deal, will that make up for what he's done? Nope. Holmes says Adam will never get the blood of those six children off his hands. "That doesn't mean you shouldn't try." Adam concedes: "I'll sign the papers. I'll tell you where we live. That's where you'll find the girl."
Somewhere! A creepy, sweaty guy who's not wearing a shirt gives a young girl a gross-looking sandwich. And then the police bust in behind a riot shield! Samuel has a gun! But he shoots himself not the girl.
Holmes stares at Samuel's body. Mariana's okay, although she's still terrified. Holmes muses, "This isn't what I was expecting." He thought Samuel would be more virile, but he has a back brace from fused vertebrae. I'm not 100% sure that Holmes is correct in his belief that someone with a strong personality is necessarily going to be a big, strong man. But it's the sort of thing that Arthur Conan Doyle's Holmes would have believed, so I don't mind it. It kind of ties in with that phrenology bust he mentioned, actually. It's that sort of mindset.
Anyway! Holmes looks around Samuel's grubby little apartment. There's a bare room with a single mattress on the floor. Watson says it's where Adam slept. No, Adam slept in the Master bedroom, because that's where the broken window is. Holmes makes the grand pronouncement: "That man out there, Abbott, is NOT the Balloon Man."
Adam comes home to a darkened bedroom. Holmes turns on the light. Hey, is this Adam's old room from seven years ago or whatever? He tells Adam that Samuel's room had a bare mattress, so: "Samuel Abbott was not the Balloon Man. You were." He even checked the hairs on the pillows in the two rooms.