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The man may have lost a few pounds, but he has all the grace of a drunken mastodon.

— Sherlock regarding Mycroft, "Blood Is Thicker"

Mycroft Holmes is the older brother of Sherlock Holmes and eldest son of Morland Holmes. He worked as a restaurateur and an operative in MI6. He had been estranged from Sherlock for years, due to Sherlock's affair with his fiancé. Mycroft suffered from leukemia and afterwards was looking to improve his relationship with Sherlock. Mycroft died in July 2017 of an intracranial hemorrhage.


Season 2[]

Sherlock brings Watson to London at the request of DCI Hopkins in order to track down his old police colleague, Gareth Lestrade. Sherlock finds his London residence, 221B Baker St. has been totally remodelled and discovers that his brother Mycroft is living there. Mycroft introduces himself to Watson and the brothers explain the acrimony between them to her which includes Sherlock sleeping with Mycroft's fiance to prove she was a gold-digger. Watson is surprised as Sherlock never mentioned Mycroft to her. Sherlock becomes angrier when he discovers that Mycroft gave away all his possessions that were in 221B. Despite the hard feelings, Mycroft insists they stay. While Sherlock leaves to find Lestrade, Watson rests and in the morning, discusses her relationship with Sherlock. Mycroft is surprised that she's Sherlock's friend.

S02E01-Mycroft meets Watson
I'm Sherlock's brother.
Watson leaves to help Sherlock and Lestrade with a case and Sherlock discovers that Mycroft has invited Watson to dinner at one of his restaurants. Sherlock is protective of Watson and warns her that Mycroft wants to sleep with her. He then accuses her of wanting to sleep with him. At dinner, Mycroft reveals that he had leukemia (which Watson deduced) and that he regrets the bad relationship he and Sherlock have. He asks her advice on the best way to heal it and become Sherlock's friend. Mycroft texts Sherlock to meet him at a storage centre. He confesses that he didn't give away Sherlock's possessions but stored them at the centre. He says he learned from Watson that he must have Sherlock's attention when telling him something important and then blows up Sherlock's possessions. Mycroft says he forgives Sherlock for everything and that things are different between them now.[1]

S02E01-Mycroft Watson dinner
I want to know how you did it.

S02E01-Mycroft Sherlock explosion
Things are different between us.

Mycroft surprises Sherlock and Watson with a visit to NYC in which he indicates he's opening a restaurant, Diogenes, and that an old acquaintance of Sherlock's needs his help. Sherlock and Watson discover the acquaintance is Nigella Mason, Mycroft's former fiancé who Sherlock slept with in order to prove Nigella's intentions towards Mycroft were monetary. Nigella explains that her divorce from a Marquess came with a champion stud race horse, Silver Blaze. The stable was broken into and the stable head, Mason, (her new lover) was killed and intent to poison Silver Blaze discovered. She'd like to find the culprit. She inadvertently reveals that Mycroft has leukemia. Sherlock wants nothing to do with her and leaves. At the Brownstone, Mycroft explains that Nigella found a bone marrow donor for him and, that if Sherlock helps, it'll prove that Sherlock sleeping with her is a thing of the past. He tags along as the stables are investigated and Sherlock finds that an assassin for the Robles drug cartel is behind the murder.

003 The Marchioness episode still of Mycroft Holmes, Joan Watson and Sherlock Holmes
Mycroft at Diogenes before its opening.
After Nigella survives a near miss from the assassin, she denies any ties to the cartel. While Mycroft cooks dinner, Sherlock discovers the stable that the cartel head, Joaquin Aguilar, owns and that Silver Blaze studded one of his mares and produced a foal. Sherlock also discovers that Watson and Mycroft slept together while in London. After seeing the foal, Holmes deduces that Silver Blaze wasn't the stud. They confront Nigella who admits that Silver Blaze died and she passed off his brother for stud. Sherlock deduces that Aguilar knows the fraud and is seeking revenge. They set a trap for the assassin who, after a time, is arrested. Mycroft asks Watson to be his guest at the opening of Diogenes and Sherlock settles the matter with Aguilar. Nigella meets Sherlock and Mycroft at Diogenes and is instructed by Mycroft to repay all the victims of her scam and use the money that Aguilar had given her for the fake stud services to begin a more respectable start in life, with the repayments overseen by both Sherlock and Mycroft.[2]

S02E07-Sherlock Nigella Mycroft
You're not gonna report me?
Mycroft and Holmes duel on the roof of the Brownstone with single sticks and eggs on the pates of their helmets. Mycroft touts the virtues of London and pleads with Sherlock to join him for dinner at Diogenes. Having been stood up for dinner for several nights by Sherlock, Mycroft phones Watson and wakes her up, pleading with her to ensure Sherlock meets him for dinner that evening. Sherlock has dinner with Mycroft who gives him the keys to 221B Baker St. but Sherlock refuses them. Mycroft lies that their father is unhappy that Sherlock has remained in NYC and that he may withhold Sherlock's trust money (which he uses to pay Watson) and evict them from the Brownstone. He reminds Sherlock that he's making decisions for two now and to consider returning to London.

S02E08-Sherlock Mycroft joust
You were a no-show at the opening.
Mycroft visits the Brownstone before he returns to London. Sherlock gives him a letter to deliver to their father with his decision to stay in NYC and, his thanks. Mycroft understands how difficult this was for Sherlock. At Diogenes, Mycroft rips Sherlock's letter up and calls an unknown person. He says his gambit to have Sherlock move back to London has failed ans since there's little chance Sherlock will talk to Morland, his lie won't be discovered. He indicates they'll have to come at "the problem" in a different way.[3]

008 Blood Is Thicker episode still of Mycroft Holmes
He's decided to stay.
Mycroft shows up at the Brownstone and makes dinner for Watson, Sherlock and Ms. Hudson and invites Watson alone to auditions for a dessert chef. Sherlock accuses him of returning to sleep with Watson. At Diogenes, Mycroft tells Watson he'd like to pursue a relationship with her. She is interested but concerned how Sherlock will complicate things. The next day, Sherlock shows up at Diogenes and tells Mycroft to stop pursuing Watson. Mycroft accuses Sherlock of hoarding Watson to himself and not being concerned for her happiness. Sherlock recognizes a patron as a high-ranking member of a French criminal organization, "Le Milieu" and believes Mycroft is involved with them. Watson meets Mycroft for lunch and says that she can date Mycroft but first must get her own place. She notices the Milieu patron, Marchef, and takes a photo of him. That evening, Watson goes to Diogenes to warn Mycroft about the Milieu member but Mycroft isn't there. She follows Marchef outside and is kidnapped by him.[4]

S02E21-Ms Hudson and Mycroft
You are not included in the invitation.

S02E21-Mycroft asks Joan out
I'm so flattered.

Mycroft tells Sherlock that Watson has been kidnapped by Le Milieu and that he's been working with them in exchange for money to keep the restaurant going. In exchange for Watson, they want a list of banking customers and their financial details downloaded by Pierce Norman, a VP at Swiss bank Credit Versoix given to them in 48 hours. Sherlock is furious but agrees to find the list after which Mycroft must never see him or Watson again. Mycroft suggests they start at Credit Versoix where they gain access as Morland's sons. Sherlock inspects Norman's office with Versoix's security head, Kurt Yoder. Sherlock finds a hidden game console which he destroys in a tantrum. Upon exiting Versoix, they are picked up by NSA Agent McNally. Sherlock lies that they are working for a foreign government friendly to the USA and will share the list when found. Satisfied, McNally ominously mentions Diogenes and its client to Mycroft.

S02E22-Sherlock grabs Mycroft
I knew you were an idiot...
At the Brownstone, Mycroft receives a threatening call to provide the caller with the list. Using Norman's ID on the hidden game, Sherlock learns his game contact and questions him with Mycroft and find a country house Norman frequents. Sherlock finds Norman's buried body at the house and deduces he was killed before the list was stolen and by a confidant. They call Yoder to the Brownstone, tase him and under threat of torture, he reveals the hard drive with the list is in his car. As Sherlock is calling the NSA for backup when the list is given to Le Milieu, Mycroft tases him and takes Yoder and the list and calls his contact to report his success. Mycroft meets Le Milieu, provides them the list and Yoder but is double-crossed. Just before Le Milieu shoots him and Watson, he says "paint it black" and Le Milieu are shot. A team of British special forces arrives on the scene and he tells a shaken Watson that he has explaining to do.[5]

S02E22-With Norman's body
But this, this may be our salvation.

S02E22-Mycroft Watson at Milieu massacre
There's a great deal I need to tell you.

Furious, Sherlock returns to the Brownstone to find Watson is fine and learns that Mycroft has been an informant for MI6 for a decade. He learns criminal group's secrets and became a clearing house of predicting how to take down the groups. They see Mycroft's handler Tim Sherrington who asks Sherlock to solve a case, to Mycroft's surprise. A former MI6 analyst, Arthur West, was murdered even though he was retired. Sherrington wants Sherlock to look into it since the NYPD has the case. Mycroft is against Sherlock taking it but he does. Mycroft waits on the steps of the Brownstone and tries to apologize to Watson but she never wants to see him again and says she can't believe anything he says. Mycroft understands and leaves.

S02E23-Mycroft apologizes
Sherlock and Watson discovers West had info of an MI6 mole tattooed on his arms. They also find out that Mycroft had gotten out of MI6 but had to return. Later, Sherlock learns the handgun used to kill West has turned up with Mycroft's fingerprints on it. Watson goes to Myrcroft's apartment to find out why he went back to MI6. He tells her that when Sherlock was an addict, Sherlock unwittingly worked for a financier of terrorism. The plot was foiled but Mycroft agreed to come back so that Sherlock would avoid jail time. All his sacrifices have been for Sherlock who has no idea what Mycroft has done for him. Watson kisses him and they sleep together. Sherlock realized Mycroft is being framed for West's murder. He breaks into Mycroft's apartment and surprises Watson and Mycroft in bed to tell them the news.[6]

S02E23-Mycroft w gun
You're being framed for murder and treason.
Mycroft thinks Sherlock concocted the frame-up until Sherlock starts Mycroft's car which explodes. Sherlock hides Mycroft in a building being managed by Ms. Hudson. He also says that he's told MI6 that Mycroft is the mole so that he'll be able to work with them to "find" Mycroft and bring down the real mole. Sherlock meets with Sherrington and MI6 who won't give him Mycroft's files but he indicates that if he "finds" Mycroft, he'll inform them. Mycroft tells Watson a criticism a 15 year old Sherlock made to his father which drove him to work with MI6 which he now considers idiocy. Holmes deduces that the tattoos on West's arm indicate dates and places the mole gave information to a source in NYC. Watson deduces that Sherrington and Mycroft's travels matched the info and Sherrington is the mole. Sherlock lies to Sherrington when he calls for an update that Mycroft made a money transfer to fund his escape.

S02E24-At library
We need to prove that he's guilty of murder, before he manages to find you.
Captain Gregson tells Sherlock that he is putting out a Want Card on Mycroft. Sherlock sees Mycroft to let him know that Watson told him why Mycroft re-joined MI6 and that he is going to make amends and fix Mycroft's situation. Mycroft surprises Sherrington eating at a pub and discretely points a gun at him. Sherrington insincerely apologizes and admits to treason because he wasn't promoted. He says if he's killed that a letter will be mailed to Le Milieu detailing Mycroft's role in their downfall and that Sherlock and Watson will be likely targets as well. He offers to take Mycroft somewhere quiet and kill him. Holmes discovers the man Sherrington was giving secrets to, Julien Afhkami, committed murder which he is able to prove. Afhkami admits to all dealings with Sherrington which clears Mycroft.

S02E24-Mycroft in pub
I die a traitor and you get away with everything.
Later at the 11th Precinct, Detective Bell tells Sherlock a body is in the Morgue. It's Sherrington, so Gregson puts out a new Wanted message for Mycroft. Mycroft is waiting at the Brownstone for Sherlock and Watson. He explains that Le Milieu killed Sherrington after Mycroft talked to the NSA and they in turn let Le Milieu know how Sherrington had compromised them. The NSA then faked Mycroft's death in a fire in the kitchen at Diogenes. Sherlock deduces that Mycroft will need to disappear. Furious, Watson leaves since she and Sherlock were working to fix the situation without drastic measures. As Sherlock insults Mycroft's perceived sloth, Mycroft hugs him and says he loves him and then leaves...forever.[7]

S02E24-Mycroft hugs Sherlock
I love you brother.

Season 6[]

Looking to mend his relationship with his brother, Sherlock tries to make contact through a Cayman Island banker Mycroft uses. He discovers that Mycroft died in July 2017 of an intracranial hemorrhage in a hospital in Timaru, New Zealand.[8]

S06E09-Holmes Watson learn Mycroft is dead
What's happened?


Great Intelligence[]

Mycroft's intelligence rivals that of his brother, Sherlock. It was sufficient to catch the notice of MI6, British Intelligence, and for them to use him as an analyst. Although both he and his brother have stated that Sherlocks intelligence surpasses his own.

Single Stick[]

Mycroft is formally trained in single stick.


  • He owns a two Michelin-star restaurant In London where he invited Watson for dinner in order to understand how to be Sherlock's friend.[1]
  • Mycroft was arrested for possession of pot by the Cambridge police in 1984.[7]
  • One of Mycroft's first restaurants was "Le Val Gielgud."[9]
  • In 2016, Watson learns from Morland that Mycroft is alive on a Grecian island. Sherlock tells Watson that Mycroft has a webbed toe.[10]
  • Diogenes is named after the club Mycroft frequented in London in Conan Doyle's Sherlock Holmes books.


Our relationship is entirely genetic. He's an embarrassment.

— Sherlock's opinion of Mycroft, "Step Nine"



  1. 1.0 1.1 Season 2, episode 1: "Step Nine"
  2. Season 2, episode 7: "The Marchioness"
  3. Season 2, episode 8: "Blood Is Thicker"
  4. Season 2, episode 21: "The Man With the Twisted Lip"
  5. Season 2, episode 22: "Paint It Black"
  6. Season 2, episode 23: "Art in the Blood"
  7. 7.0 7.1 Season 2, episode 24: "The Grand Experiment"
  8. Season 6, episode 9: "Nobody Lives Forever"
  9. Season 4, episode 9: "Murder Ex Machina"
  10. Season 4, episode 19: "All In"