‘Sherlock’ season 4, episode 3 synopsis: Plot details for third and final episode

‘Sherlock’ season 4, episode 3 synopsis: Plot details for third and final episode
Source: BBC
Source: BBC

In what could end up being the penultimate episode of BBC's Sherlock, episode two gave us the likely answer to James Moriarty's ominous, post-mortem riddle: a secret Holmes sibling. Using an array of disguises, Eurus Holmes has snuck her way into the lives of Sherlock and John Watson as John's therapist, a flirty bus passenger and the daughter of a serial killer. 

Now that Eurus has been revealed, pointing a gun at John's head before pulling the trigger at the episode two end credits (though, of course, John isn't dead), what does that mean for the season four finale?

Source: BBC/YouTube

The synopsis for episode three, titled "The Final Problem," suggests that Eurus is Sherlock and John's greatest challenge yet — though in fairness, the series said the same thing about Culverton Smith last week, and practically every villain from seasons prior. But the plot details also hint that the season four finale could ultimately be a series finale for Benedict Cumberbatch's take on the world's greatest detective. 

Per PBS

In the final episode of this new season, long buried secrets finally catch up with the Baker Street duo. Someone has been playing a very long game indeed and Sherlock and John Watson face their greatest ever challenge. Is the game finally over?

It certainly does feel like Sherlock is reaching its endgame, and not just because the rising stardom of Cumberbatch and Martin Freeman is making it harder for the series to find time to film. This iteration of Sherlock has already matched wits with a plethora of worthy adversaries — it's hard to imagine a better final antagonist than his long-lost sibling, who may have been pulling the strings from afar the whole time. 

The Sherlock season four finale, "The Final Problem," airs Sunday at 7 p.m. Eastern on PBS. 

How much do you trust the information in this article?

Miles Surrey

Miles is a staff writer at Mic, covering culture. He is based in New York and can be reached at miles@mic.com.

MORE FROM

Debate: Is director Christopher Nolan the best or the worst filmmaker of our time?

Mic asked two staff members to debate the relative merits of award-winning director Christopher Nolan and his movies.

‘The Vampire Diaries’ ending could be what saves ‘The Originals’

The end of 'The Vampire Diaries' could mean a new beginning for 'The Originals.'

Let’s needlessly overthink these ‘Game of Thrones’ photos from “Stormborn”

Sam's still at the Citadel, looking miserable.

BBC just shut down every misogynist mad about a female Doctor Who

The Doctor was always destined to become a woman.

Noah Hawley is a busy man. Here’s a running list of everything he’s working on.

I hope he finds time to, like, sleep and be with family.

19 must-see panels and events at San Diego Comic-Con this year

Comic-Con can be overwhelming. This list will give you the highlights.

Debate: Is director Christopher Nolan the best or the worst filmmaker of our time?

Mic asked two staff members to debate the relative merits of award-winning director Christopher Nolan and his movies.

‘The Vampire Diaries’ ending could be what saves ‘The Originals’

The end of 'The Vampire Diaries' could mean a new beginning for 'The Originals.'

Let’s needlessly overthink these ‘Game of Thrones’ photos from “Stormborn”

Sam's still at the Citadel, looking miserable.

BBC just shut down every misogynist mad about a female Doctor Who

The Doctor was always destined to become a woman.

Noah Hawley is a busy man. Here’s a running list of everything he’s working on.

I hope he finds time to, like, sleep and be with family.

19 must-see panels and events at San Diego Comic-Con this year

Comic-Con can be overwhelming. This list will give you the highlights.