In the first season of Elementary, we saw Sherlock and Joan’s relationship evolve from sober companionship to partners and lifelong friends.
Highgate Cemetary – London, England
A drunk, possibly unhinged Inspector Lestrade (Sean Pertwee) crashes a funeral. He terrifies the group of mourners by pulling out a hand grenade. He then accuses the dead man of slandering his name, thereby ruining Lestrade’s career. He then accuses the dead man’s son Lawrence Pendry (Rufus Wright) of murdering his own wife and getting away with it due to his father’s money and resources.
Washington Square Park – New York
Sherlock (Jonny Lee Miller) tells Joan (Lucy Liu) about his theory on a case their working on – there’s a crime syndicate using carrier pigeons to communicate. When their prime suspect arrives to grab one of the carrier pigeons, Sherlock ends up having to chase him across the park.
In the end, it’s Joan who captures him, using the self-defense tactics that Sherlock taught her.
After Captain Gregson (Aidan Quinn) and Detective Bell (Jon Michael Hill) congratulate Sherlock and Joan on solving the case, Sherlock gets a call from England. He informs Joan that they’ll need to go to London in order to help Sherlock’s old colleague, Inspector Lestrade.
Sherlock and Joan’s Loft
Sherlock tells Joan about his relationship with Lestrade. Sherlock worked with Lestrade, back when Sherlock was working for the Scotland Yard in London. Sherlock would solve their cases and Lestrade got credit for Sherlock’s work. When Sherlock left for New York, Lestrade was left without his crutch. Sherlock feels guilty about abandoning his old colleague.
We get glimpses of some of London’s major sites – the London eye, Buckingham Palace, Trafalgar Square.
Now that they’re in London, Joan suggests that this would be a good opportunity for Sherlock to work on Step Nine of his recovery – making amends with the people he’s wronged. Sherlock is skeptical.
They meet with DCI Hopkins (Tim McMullan) at the Scotland Yard building who tells them that after Sherlock left for New York, Lestrade began to struggle. He cut corners and did whatever it took to close cases. The case that ruined Lestrade’s career had to do with the aforementioned Lawrence Pendry making a 999 call about an intruder in his home. Pendry had claimed that his wife, Mary, had been accidentally shot during Pendry’s struggle with the intruder, but Lestrade had a hunch that the scene was staged. Pendry’s dad – London’s biggest media mogul – took this opportunity to slander Lestrade’s name. As a result, Lestrade was suspended, pending an investigation.
Then two weeks later, Lestrade made an appearance at Pendry’s dad’s funeral, brought a fake hand grenade, and now he’s missing. Hopkins called Sherlock to London because he needs Sherlock’s help to find Lestrade. However, Sherlock’s interest has now also been piqued regarding the Pendry case.
At (the very famous) 221B Baker Street, Sherlock’s old loft, Joan meets Mycroft (Rhys Ifans) and is shocked to learn that Sherlock has a brother. Sherlock never mentioned having a brother before, and we quickly learn why that is – Sherlock and Mycroft do not get along. Neither is too pleased to see the other.
Mycroft tells Joan about Sherlock sleeping with Mycroft’s fiancé… seven times. Sherlock is visibly embarrassed but denies any wrongdoing – the only reason Sherlock had sex with her was to prove that she was only after the family fortune. It also seems that Sherlock’s father gets along better with Mycroft, though Sherlock insists that Mycroft is lazy and lacks ambition.
Sherlock is appalled to learn that their father left 221B Baker Street to Mycroft. Despite the brothers’ tension, Joan convinces Sherlock to take Mycroft’s invitation to stay with him while they are in London.
Later, Sherlock manages to track Lestrade down at a local pub. They hash things out, and Lestrade tells Sherlock that despite everything that’s happened between them, he wants to work with Sherlock one last time. Sherlock agrees to one last case, and calls Joan to meet them at Lestrade’s hideout. The three of them comb over the evidence files until they make a few breakthroughs.
At Sherlock’s behest, Lestrade writes a fake suicide note saying that he’s going to kill Pendry. Sherlock uses the fake note, along with the lie that Joan is the number one home security expert, to inspect Pendry’s home.
After they leave, Sherlock tells Joan that Lestrade is right about everything – Pendry did kill his wife, they just have to prove it.
Pendry shot his wife. He then disassembled his plastic gun and dropped the pieces into a bottle of acetone. He hid the evidence in a milk bottle. Just knowing this isn’t enough to get Lestrade off suspension and Pendry in custody, however – they need to find out where and how Pendry made his gun.
Sherlock decides to go solo so Joan can have dinner with Sherlock’s brother, Mycroft. Joan insists Mycroft isn’t trying to seduce her and that nobody will be having sex tonight. Sherock thinks otherwise, and he wants to see which of them is correct.
When Joan arrives at Mycroft’s restaurant, she notices the restaurant has been cleared out. Sherlock’s words got to her, because she makes it clear that nothing romantic is going to happen.
Mycroft tells her that he actually wanted to talk to her about Sherlock. Joan correctly guesses that Mycroft had been ill, and that’s how he ended up losing so much weight. She noticed the mark on his hand and guessed that he’d had a bone marrow transplant. Mycroft tells her that he’s been reflecting on his relationship with his brother in the past few years of his illness. He wants to know how Joan became Sherlock’s friend, so that he might help repair that relationship.
Elsewhere in the city, Sherlock and Lestrade go through a list of people who’ve bought 3D printers recently. Sherlock tries awkwardly to do step nine of his recovery process and make amends with Lestrade, but they get distracted when Lestrade finds the name he’s looking for. They go to confront the man Pendry paid to buy the printer only to find him dead.
Later, Joan and Sherlock process the scene and figure out that Pendry must have built himself a second plastic gun and gone to tie up loose ends, only to have the gun explode in his hands. Pendry’s accomplice ended up dead anyways, but now Joan and Sherlock have the proof they need to arrest Pendry for murder. Case closed.
Lestrade ends up taking all the credit for Sherlock’s insights again, and as exasperated as he is Sherlock leaves him to it, not wanting any of the spotlight for himself. At the end of the episode, Mycroft and Sherlock finally have their own version of a heart-to-heart conversation – though Mycroft never does tell Sherlock about his health problems, and also ends up blowing up all of Sherlock’s London possessions. Job done and relationships successfully repaired, Sherlock and Joan head back to New York.