The episode starts with Holmes, Watson, Captain Gregson and Detective Bell arriving at the home where little Mariana Castillo was snatched. She is presumed to be the seventh victim of the 'Balloon Man', a serial killer who got his name after leaving 'Thank You' balloons to the parents of the first child he snatched, 12-year-old Adam Kemper, in 2005.
Sherlock spies the parents of the missing girl preparing to make a televised plea for the safe return of their daughter and stops them, pointing out that there is a correlation between how long the Balloon Man's previous victims were kept alive and their parents' media exposure. He instructs them to "keep him hungry" and vows that they will get their daughter back if they do everything he says.
After questioning the father's ex-mistress, who Sherlock worked out existed thanks to a wine bottle, worn out corkscrews and mail from Long Island, they learn that Mariana was abducted in a brown truck. The vehicle is later tracked down and the police give chase, eventually dragging out its driver, a babyfaced teenage boy, and cuffing him. Sherlock recognises a birth mark on the boy's face and identifies him as Adam Kemper.
The police try in vain to get the boy to talk and Watson points out that he may have formed some kind of twisted attachment to the Balloon Man. Sherlock wonders whether Adam had a part in the later killings and Captain Gregson gives him five minutes to speak to him.
Sherlock reins himself in and attempts to connect with the boy on a level that the character so far has shied away from. He makes progress, and just about manages to get Adam opening up about his love for the Balloon Man when his parents arrive at the station accompanied by a lawyer, pushing for him to have immunity in return for him ratting out the killer.
The aborted interview gives them an extremely slim chance of identifying the killer when Sherlock points out that Adam inadvertently revealed that he works nights. Sherlock later comes up with the theory that the killer has been singling out his victims via his jobs and now delivers papers.
Posing as a subscriber who wants to give the delivery boy a belated tip, Sherlock finds out that they are after a man named Samuel Abbot. SWAT teams target an address linked to him and discover it empty, aside from a bunch of balloons with a USB attached. Sitting on it is a video file of the killer threatening to murder the missing girl if the cops do not return "his son" Adam.
With the police blocked from speaking to Adam due to the immunity deal, Sherlock steps in and tries to talk to the boy. It's strange to see our protagonist, normally so outlandish and flamboyant, reducing his voice to a whisper as he listens to Adam's internal conflict about watching and helping the man he loves do such terrible things. "You will never get that blood off your hands," Sherlock tells him. "But that doesn't mean you shouldn't try."
Adam finally agrees to turn in his father and as a SWAT team turns up at Abbot's home, he turns the gun on himself. Don't be nipping off to the toilet just yet though - this is another one of those faux endings that already seems to have become an Elementary convention in just three episodes.
Looking over Abbot's body with Watson, Sherlock can't help but question how a man so "feeble" could have tormented Adam for years. His scepticism sends him racing round the house, and he soon declares that Abbot is not the Balloon Man.
Holmes's suspicions stem from a comment Adam made at the station about having cut his hand trying to open a window in his bedroom, even though there is cracked glass in the lavish, master room, not the squalid box where Abbot supposedly made him sleep.
Sherlock confronts Adam, quietly incensed about being tricked. The boy admits that he enjoyed watching his parents beg for him to be returned safely and wanted to replicate the thrill with the other children. He turned the tables on his captor through psychological and then physical abuse, with the hostage switch a contingency plan that had always been in place should he ever get caught. The problem is he's untouchable because of the immunity deal.
Sherlock meets with Adam again later, as he nonchalantly talks about his murders. There's a slight loophole in the immunity deal though - he's only safe from crimes committed "in consort" with Abbot, and one of the murders can be traced back to a period when the elder man was in traction with a back problem that persisted until his dying day. With the police approaching, Adam reminds Sherlock that only one murder can be pinned on him and he'll be free soon enough.
For daring to plunge so much deeper than previous episodes - not just with the upsetting central crimes, but also by showing Sherlock's fallibility - 'Child Predator' is easily the highlight of Elementary's debut season.
Another plus point is that Watson's dynamic with Sherlock and the role she has to play is becoming slightly clearer. Holmes realises her simply being there to listen to his theories helps build a clearer picture of the crime. He starts to see her as an asset, as equals, after starting the episode telling her to only speak when she is spoken to.
The character herself though is moving a bit into quirky sidekick territory though, encouraging Sherlock to join her in some goofy looking exercise to stay awake. It'd be nice to see her get a bit more hands on in a future episode or two.
It might be needed, given that this is the closest that Miller's Holmes has come to being defeated. He discovers the truth about Adam far too late, and the crook's jailing is a hollow victory.
Sherlock makes a big step in opening up and trying desperately to empathise with fellow human beings, rather than see them as subjects to be analysed, and this proves to be his downfall. We're sure this betrayal will weigh heavy on the character's mind and seep into future mysteries.
What are your thoughts on this week's Elementary? Leave your comments below!