Warning: This article contains MAJOR spoilers for all of Sherlock Season 4. Read at your own risk…
In Sherlockseason four, we learned the truth about Sherrinford, Eurus, and Redbeard. Here’s everything you need to know about the biggest of season four’s mysteries…
Who is Eurus Holmes?
In “The Lying Detective,” we got confirmation that Sherlock and Mycroft do have another sibling, a sister named Eurus (the very talented Siân Brooke).
Eurus has been hiding in plain sight since the beginning of season 4. In “The Six Thatchers,” she appeared as “E,” the woman John flirted with on the bus and, later, via text. In “The Lying Detective,” Eurus disguises herself both as John’s newest therapist and as a woman claiming to be Faith Culverton who first puts Sherlock onto the Culverton case.
In the final scene of the episode, Eurus reveals herself to John. Like her brothers, she is a master of disguise, incredibly smart, and unfortunately (in this case) adept with a gun.
In mythology, Euros/Eurus is the Greek god of the east wind who was thought to bring rain and warmth. Mycroft and Sherlock has been going on about “the East Wind” since season 3. In “His Last Vow,” Sherlock tells John:
The East Wind takes us all in the end… It’s a story my brother told me when we were kids. The East Wind — this terrifying force that lays waste to all in its path. It seeks out the unworthy and plucks them from the earth…That was generally me.
Later, at the end of the episode, when Mary asks if Moriarty is back, John tells her: “Well, if he is, he’d better wrap up warm. There’s an East Wind coming.” Basically, the foreshadowing to Eurus’ return have been many.
In “The Final Problem,” Eurus lures Sherlock, Mycroft, and John to Sherrinford in order to put them through a series of tests. We learn over the course of the episode that Eurus was shipped off to Sherrinford at a very young age after presumably killing Sherlock’s best friend, Victor Trevor, threatening to kill Sherlock, and burning the Holmes’ family house down.
Mycroft was the only Holmes aware that Eurus was still alive. He told his parents that she had died in a fire, while Sherlock had no memories of his sister until they were jogged by her return.
Eurus and Moriarty started working together to bring the Holmes brothers down after Mycroft allowed Moriarty a five-minute unsupervised visit on Christmas Day, five years before the events of “The Final Problem.”
As of the end of Sherlockseason four, Eurus was locked away in Sherrinford, though she seems to get occasional visits from the rest of her family members, including Sherlock, who plays the violin with his sister.
Who is Sherrinford?
Sherrinford is not a who, but a what: the high-security island prison facility where Eurus Holmes and at least three cannibals are kept.
Mycroft, Sherlock, and John travel to Sherrinford in “The Final Problem” in an attempt to discover how Eurus has been sneaking out of the facility. (It’s seriously impressive. She’s basically Magneto-ed there.) Unbeknownst to them, Eurus has already taken over the facility by brainwashing the people who work there.
Where does the name Sherrinford come from?
So why does Sherlock Holmes fandom equate Sherrinford with a Holmesian brother? That’s kind of a long story. Sherrinford was one of Sir Arthur Conan Doyle’s potential names for the character of Sherlock Holmes. The name was found in Conan Doyle’s notes.
Sherlock Holmes fandom latched onto the name and, when William S. Baring-Gould wrote a fictional biography of Holmes, he included Sherrinford as his oldest brother. As country squires in 19th century England, the eldest Holmes brother would have had to stay home to manage the family estate, freeing up Mycroft and Sherlock for different kinds of lives and adventures, so this actually makes some sense within Sherlock Holmes canon. Otherwise, it seems unlikely that Mycroft would have had the time and lack of responsibility to become a civil servant, a frequent career choice of not-eldest-brothers of the time.
It’s worth noting at this point that, in Sherlock‘s “The Six Thatchers,” Mycroft moves a Reigate Square takeaway menu to find the “13th” note. “The Adventure of the Reigate Squire” is a Sherlock Holmes story. Though it is more notable for filling in some of Watson’s pre-Holmesian past, perhaps Sherlockwill take a different route with its narrative introduction, using it as a chance to explain more about Sherlock’s past and his connection to a potential older brother.
Other appearances of Sherrinford over the years include his turn in Doctor Whonovel All-Consuming Fire, where he is the member of a cult that worships a telepathic alien slug. (Please let Sherlockdraw on this interpretation.) Holmes is forced to shoot his brother in order to save Watson. In Call of Cthulhurole-playing game,Sherlock must prove his brother innocent of an accused murder. Sherrinford also appears in a Sherlock Holmes-inspired Italian comic series, where he is depicted as nine years older than Sherlock.
Who is Redbeard?
Prior to Sherlock season four, Redbeard was always depicted as Sherlock’s childhood dog, a name Mycroft liked to bring up whenever Sherlock was getting particularly unmanageable.
In “The Final Problem,” we learn the horrible truth: Redbeard was not an Irish setter, but a little boy, Sherlock’s childhood best friend, a boy named Victor Trevor. Victor and Sherlock would play pirates together. Sherlock was Yellowbeard and Victor was Redbeard.
Eurus was jealous of Sherlock’s best friendship with Victor, so she trapped Victor at the bottom of a well and gave Sherlock and Mycroft a riddle to find him. They didn’t, and Victor was never found — until years later when John Watson was trapped down that same well.
Why did Sherlock always remember Redbeard as a dog, not a boy? To protect himself. He rewrote his memory to forget Eurus and to believe that Redbeard was a dog because the truth was far too terrible for him to stand. Still, the event changed Sherlock.