"The Reichenbach Fall"
The finale of the second series, this chapter will have you on the edge of your seat. The episode gives us both the best and worst of Sherlock Holmes: Sherlock becomes so tangled in the minutiae of a code his archenemy Moriarty has given him that he fails to see the bigger picture. When Moriarty hashes out a plan to ruin Sherlock’s reputation and kill him, Sherlock must attempt to save his good name while also solving his current case.
Related: 10 Books for Sherlock Holmes Fans
"A Scandal in Belgravia"
In a meeting at Buckingham Palace with Mycroft, it is brought to Sherlock and John’s attention that a dominatrix has taken potentially ruinous pictures with a woman from the royal family. Sherlock knows precisely what he has to do: figure out Irene Adler’s cell phone password before the photos end up in the wrong hands. But will Sherlock be able to solve this one without putting lives at risk?
"The Final Problem"
People play countless games in Sherlock, but in this 13th (and possibly final) episode of the series, the game is particularly long and grueling. When Sherlock discovers that someone who has been in hiding for several years has been aiding and abetting the diabolical Moriarty, multiple mysteries emerge and more than one life is put on the line. This is Sherlock and John’s biggest challenge yet: will they win the game or is it over?
"His Last Vow"
There are many people Sherlock is less than fond of, but only one whom he hates with a passion: Charles Augustus Magnussen. A newspaper owner with an affinity for blackmail, Magnussen has been partaking in frequent meetings with government officials in attempt to extort them. When critical letters are stolen and the suspect remains unidentified, Sherlock knows exactly who to blame.
"The Great Game"
This finale of the first series is explosive—literally and figuratively. When a government employee working on a top-secret project dies mysteriously, Mycroft commissions Sherlock to investigate the death, a case that Sherlock hands over to John, despite his preoccupation with a new love interest. Meanwhile, a mysterious criminal who forces victims to wear explosive vests taunts Sherlock by giving him deadlines to solve unconnected cases. Every deadline Sherlock fails to meet, another victim dies.
"A Study in Pink"
The first episode of Sherlock launched us into the show's mysterious, action-packed world. Sherlock begins to investigate a chain of seemingly unrelated deaths, which are connected by a poisonous pill that each victim consumed before dying. When Sherlock finds himself in the same dire situation as the victims, face to face with the criminal, the stakes are high. This thrilling episode sets a precedent for what’s to come.
"The Sign of Three"
Sherlock has confronted many a tough feat, but there is one that proves to be his most arduous challenge of all: delivering the Best Man speech at John’s wedding. Unsurprisingly, since some sort of peril is always a guarantee in Sherlock, serious danger lurks at John’s wedding reception. After putting on a smile and surviving the wedding, Sherlock must bolt out of the reception to catch a killer who remains at large.
Related: The Criminal Twin of Sherlock Holmes
"Many Happy Returns"
This seven-minute long episode, though technically not a full Sherlock episode, is a prequel mini-episode to the third series of the show. It’s still gripping television, so we’re sharing it anyway. In the episode, crimes that span from Tibet to India to Germany emerge while Watson and Lestrade try to cope with Sherlock’s supposed death. Despite the public ‘death’ of Sherlock, a series of brilliantly solved cases leads forensic scientist Philip Anderson to believe the consulting detective is still alive.
Featured still from "Sherlock" via BBC One