A woman steps in a red puddle and finds a severed hand. Sherlock says the owner of the hand is dead and he knows where the body is. The body was dragged when the car was impounded and remains under the car.
Gregson is in interrogation with bruised knuckles. He refuses to say why he hit a fellow cop.
The victim, Moshe, owned Postal Unlimited where Sherlock discovers a hidden safe and a coded ledger.
A female officer bursts into Gregson's office, upset that he hit her partner. Gregson counters that he had to since the cop laid hands on her ... his daughter, Hannah.
Sherlock won't let Kitty use his computer. She asks why. He is upset because he discovered Watson wrote about their cases together.
Sherlock eventually realizes Moshe was smuggling diamonds. A briefcase with a bloody handcuff is found in a dumpster with the diamonds still inside.
Sherlock believes a weight lifter pulled Moshe's hand off. They go to Richie's Gym to investigate. Sherlock approaches one of the suspects, Dana, and accuses him of killing Moshe. Dana tells him to back off and Sherlock challenges him to arm wrestle, British rules, but Sherlock hits him in the nose instead. Now they have a DNA sample.
Gregson is supposed to shake Stotz's hand in front of other cops, which he doesn't want to do. Hannah says she and Stotz are over and she doesn't want people to look at her like a victim.
The DNA matched Dana. He confesses and says that the guy who hired him had an additional three targets.
Sherlock and Kitty go back to Postal Unlimited to talk to the clerk, Amit. He tells them about Leonard, a jewelry dealer, who got physical with Moshe in front of him and two customers. They are all on the hit list.
Kitty tells Gregson she knows about the situation with his daughter. She says he is doing the right thing by shaking Stotz's hand. After what happened to her, everyone treated her differently, which is why she wanted to start over. Hannah doesn't want to be a victim.
Bell interrogates Leonard. He denies killing Moshe. Sherlock believes him because the emails were full of American colloquialisms which Leonard does not use. Bell disagrees.
Sherlock proposes a thought experiment to identify viable suspects. Kitty thinks Amit, the clerk is the culprit, but Sherlock disagrees since he is on the hit list.
Kitty is right. Amit plotted with Kazmir's lawyer. Kazmir was paid to produce the hit list so Amit looked like a victim.
Gregson goes to the 15th and shakes Stotz's hand. Stotz tells him that he is quitting the force and asks him to let her ... the English one.... know. Gregson thanks Kitty for her help.
Sherlock tears up the nondisclosure disagreement and tells Kitty that she is free to write about her experiences.