Welcome to Elementary! A kid with a backpack leaves his home in Brooklyn, 2005. Thanks, helpful captions! A car pulls up and an unknown man says, "Hey, Adam. Remember me? Going to school, huh?" Adam does seem that suspicious, although he finds it odd that the car is full of mylar balloons that say "Thanks!" The man explains that they're for Adam's parents. And as the car drives away, the balloons are left behind, tied to a brick sitting on the sidewalk.
Now, to the present day. Watson comes downstairs in the Brownstone and says that Holmes promised to jogging with her. Her plan is that running will help him get over the drugs. Holmes, however, has stayed up all night studying the files of the Balloon Man. He only agreed to go running because he wasn't listening to her. Holmes, by the way, is shirtless and has a prominent tattoo on his back that says "26.2." I mention that because the implication is that he runs marathons often enough that he thinks it appropriate to have a tattoo about them. Watson remembers the Balloon Man's first victim, because she lived a few blocks away. Holmes references e.e. cummings and smugly predicts the exact time when he'll be called in to consult. But he's fifteen minutes off, because the call comes in right away. That's when he realizes he's not wearing a shirt.
To the crime scene! Detective Gregson and Officer Bell run down the timeline of the abduction. Holmes pokes at a freshly broken vine, which he figures was caused by Mariana Castillo fighting back. But he doesn't think being "a fighter" will help her, since she'll be fighting a grown adult.
Inside the Castillo home, there's a video crew about to go live. But Holmes will not have it! They won't listen to his peremptory demands to shut it down, so he sprays paint in the camera lens. And then, after he's ruined the expensive equipment, he tells the parents about the correlation he found in the files: the more interviews the parents did, the faster the children died. "The Balloon Man feeds off the public grief." That's great, but I think he could have just said that to begin with. He could even have told the police that when he got the first phone call!
Holmes strolls through the house and makes keen observations about everything. There's a phone, which he strokes in a weirdly friendly way. Watson muses about the first victim. She eventually remembers that his name was Adam Kemper. Holmes tells her to leave the room because she's distracting him with he incessant talking. In his opinion, it's okay if he talks to her, because then she's helping him clarify his thoughts. This offends her, but it's not like he asked her to hang around him all the time. And if this is what it takes to find the murderer, maybe Watson could just go along with it?