Season: Six — Episode: 21 Director: Christine Moore — Writer: Robert Doherty — Aired: September 17, 2018 — Viewers (millions): 3.10 Summary: Holmes and Watson face their greatest challenge to date when a murder investigation threatens to destroy their partnership.
No. We're much better than that. We're two people that love each other. We always have been.
— Holmes to Watson
In the wake of Michael Rowan's killing, Watson is questioned by FBI Agent Mallick. Watson's alibi is weak as she was at her parent's house, but only her mother was present. Mallick believes Watson killed Rowan as an act of obsession after he invaded The Brownstone and attacked her. Mallick plays Watson a recording of Rowan leaving an internet voicemail for William Bazemore when he was killed in which Rowan says "Joan." Watson asks for a lawyer. Holmes and Watson consult with an attorney who believes she'll have a tough time defending Watson and indicates that Mallick wants Watson imprisoned. In private, they confirm that neither of them did kill Rowan and without the NYPD's help, Holmes says they'll have to cheat in their investigation. Holmes surprises Captain Gregson at his home and asks for help which Gregson can't give as he's being too closely watched.
I wanted him behind bars too.
At the Brownstone, Holmes has Watson review Rowan's autopsy report which he stole from the Morgue. He's blown up a picture of Rowan's corpse significantly. Watson notices that Rowan's orbital bone was fractured meaning he was concussed as he died and, that the wound Watson inflicted on him when he attacked her has been stitched up by a former Vietnam war medic. Holmes has an idea who the medic might be. At a support group meeting, Holmes confronts Denny Mulgrew. In private, Mulgrew admits to helping Rowan but didn't know he was a serial killer. Rowan told him he was stabbed trying to buy drugs. He let Rowan stay at his house overnight but he left in the morning. When he learned of the accusations against Rowan, he kept quiet, fearing imprisonment. Holmes says he'll protect him from the police if he helps him.
Note the wound you inflicted.
Holmes has Watson meet him at Mulgrew's house. He asks her to don a hairnet and surgical mask so she'll leave no DNA. He finds some traces of blood splatter and that the floor has been chlorinated. Spraying luminol on the floor, he sees woman's shoe prints that are the same size as Watson's. Later at the Brownstone, Holmes remarks that they are far ahead of the FBI's investigation and posits that Mallick may be the killer. Holmes has Everyone look into her but when Watson proposes they tell the FBI about the crime scene, Holmes says that he had Mulgrew burn his house down. He impresses upon Watson how close she is to being charged with murder, which he won't allow. Questioned by FBI agents, Detective Bell lauds Watson and treats the agents with contempt. Joined by Mallick, she claims Holmes and Watson didn't follow the rules in their investigations and threatens to expose this in the cases Bell worked on with them, which would ruin his chance to become a US Marshal.
I feel ridiculous.
Not dissuaded, Bell meets Holmes and gives him everything the NYPD has on Rowan's killing. He tells Holmes that Mallick will do anything to pin Rowan's murder on Watson. Grateful, Holmes shakes his hand. Returning to the Brownstone, Holmes finds Watson has put his bees on an internet cam. (♫ Barry White - It's Only Love Doing Its Thing ♫) She explains this was the price Everyone demanded for looking into Mallick. Holmes points out that Watson is being humiliated as a member of Everyone is aroused by bees. Showing her the file Bell provided, he's discovered that the garbage found around Rowan's body came from Harlem, yet he was killed in Queens. Holmes believes Rowan's body was transported by a Harlem garbage truck. At the Harlem garage, they question mechanic Curtis Jenkins whose son Graham was wrongfully imprisoned after Rowan murdered his wife. Jenkins is thrilled Rowan was killed but denies any involvement and indicates he wouldn't help even if he knew who was involved. Holmes threatens Jenkins but Watson restrains him.
Everyone got back to us...
They proceed to the manager's office to look at surveillance video but discover that the footage was taken and the originals erased by Captain Gregson. Gregson enters his home to find it ransacked and Holmes waiting for him. Holmes tells him he knows almost everything and Gregson confirms he didn't keep a copy of the garage video. Holmes has deduced Rowan's killer was Gregson's daughter Hannah whose roommate, Maddy, Rowan murdered. Gregson relates that after Maddy's murder, Hannah got to know every aspect of Rowan's life. After he was wounded attacking Watson, Hannah knew Rowan would go to Mulgrew's house which is where she beat him to death. Hannah didn't hear Rowan say "Joan" and didn't know his killing was being recorded. Gregson helped Hannah before Mallick pinned the murder on Watson. He believes there isn't enough evidence for Mallick to arrest Watson and appeals to Holmes to let the matter lie. When Holmes points out the damage Mallick's allegations will have on Watson's life, Gregson, ashamed and angry, blames Hannah's actions on Holmes, whose life Rowan targeted with his serial killing.
She used her baton instead.
You're the door that this lunatic walked through, okay?
Gregson can't let Hannah, a cop, go to prison but Holmes says Watson is his best friend and leaves. At the Brownstone, Holmes tells Watson they should give the FBI what they've found. Watson doesn't want Hannah or the Captain to go to prison and believes Mallick doesn't have enough evidence to arrest her. When Holmes points out that Watson won't be able to adopt a child and the other impacts the allegations will have on her, Watson doesn't care. He exclaims they'll never be able to work for the NYPD again but Watson demands his support for her decision. At the waterfront, Holmes meets Hannah and tells her that despite the blame for Rowan's murder being pinned on Watson and the Captain's betrayal, Watson doesn't want to turn either of them in. She would rather take her chances but Holmes demands Hannah reveal where the murder weapon is.
So be my partner.
I think a good detective leaves nothing to chance.
Watson is called to FBI HQ where Mallick informs her that Holmes confessed to Rowan's murder through a proxy from the British consulate. A fiction that he was working for MI6 when he killed Rowan led to a deal between the US and UK and Holmes isn't not allowed to visit the US again and can't be extradited. Watson insists Holmes didn't kill Rowan and wants to speak with him. Mallick agrees with Watson, indicates Holmes is in the UK and sarcastically congratulates Watson for getting away with murder. Holmes is waiting for Watson at the Brownstone. He says he's the only person who could confess to the murder and not pay for it. Hannah gave him the murder weapon once he explained his plan. Watson believes they could have fought the accusations together but Holmes believes they would have failed. He gives Watson a heartfelt thank you for saving his life during the time when they first met. He leaves to board a plane for the UK.
Sherlock Holmes isn't America's problem anymore.
Six months later in London, Holmes interviews a new client, Lord St. Simon, whose bride disappeared from their wedding reception. While listening to Simon, Holmes complains of noise from next door which Simon doesn't hear. Apologizing, Holmes indicates he's still getting used to his new neighbors but he jumps up and yells at the wall. Later, Holmes exits 221B Baker St. and knocks on the door of 221A which is answered by Watson. He complains about the noise which Watson blames on moving furniture around. (♫ The Stones Roses - This Is the One ♫) He indicates there's been a murder and they've been summoned to Scotland Yard. They kid each other as they walk down the street.
I feel like we're exactly where we're supposed to be.
The episode title is taken from a famous Conan Doyle Sherlock Holmes quote, "when you have eliminated the impossible, whatever remains, however improbable, must be the truth" which first appeared in The Sign of the Four. Holmes also quotes it when working on a case involving a supposedly impregnable vault. ("The Leviathan")