Kitty arrives to find Sherlock and Joan waiting for her. Her kidnapper and rapist is in New York. They believe he came here intentionally. Kitty refuses to leave or hide. She is prepared to hunt him down.
A woman gets thrown into a room. The man tells her it will get worse and locks her inside.
Sherlock notes that Melanie only had one selfie on her phone. Perhaps for a profile picture for a dating site.
Gregson and Sherlock interview the man who was supposed to meet her the night she disappeared. He stood her up because she wasn't as hot in person.
Joan speaks with the bartender who remembers Melanie. She nursed one drink but had a hard time walking afterwards, which makes Joan believe she was roofied. The bartender gives Joan the phone left at her booth.
The phone belongs to a violent ex-con named Simon de Merville. They raid his place which he ran as a brothel. Gregson finds the brand used on Kitty and Melanie.
Sherlock believes Simon was injured when he killed his partner. They visit his sister who works at a hospital. She admits to patching him up, but that's it. Sherlock believes she gave him an expensive drug to sell.
Kitty visits Simon's sister, Violet. She turns off the lights, saying that she doesn't want the police to know that she visited, then pulls out her baton.
Violet goes to the precinct. She seems afraid of Kitty but shares what she knows. She has a number for Simon and calls him to let him know that she can get more drugs to sell. He calls back but doesn't need the drug. The police weren't able to track the phone, only the cell tower. But Sherlock recognizes the sound of a marine toilet flush.
They check the marinas but can't locate him. Sherlock realizes that Simon isn't hiding on a boat at a marina but on a boat at someone's home, specifically his neighbor.
They confront the neighbor who admits in exchange for the drug that he agreed to let Simon stay on the boat. The boat where Simon was staying was torched with him inside. Gregson thinks it may be over.
Gregson asks Sherlock if he knew about Kitty's visit to Violet. Kitty beat Violet and Gregson is suspending her relationship with the police.
Kitty says the body is Simon's but he is not her kidnapper. She broke the fingers of her kidnapper and his fingers have never been broken. Sherlock says she could be in denial, which angers her.
Joan arrives home and talks to her new boss, Del on her cell phone. She thanks him for being understanding. She is surprised to see Kitty who is visibly upset. She asks Joan who she was talking too. She recognized his voice. He was her kidnapper/rapist.