11 things we learned from the first Sherlock series 4 trailer

1. Moriarty is (possibly) back from the dead

Most of what we see of Andrew Scott’s master criminal in the trailer is the “Did you miss me?” clip released at the end of series 3 along with some kind of static – could this mean he’s set up something digitally to take down Sherlock?

On the other hand, the head of this man walking along a beach certainly looks familiar…

2. Something’s coming…

But we’re not sure what kind of evil Sherlock is afraid of, with the sleuth commenting that “maybe it’s Moriarty, maybe it’s not.”

3. Someone’s going to get hurt

Early in the trailer we see Martin Freeman’s John Watson standing in silhouette in front of a hospital bed – but who’s the patient?

4. Whatever happens will involve some very creepy nurses

We're not sure why they're here, but they don’t seem very friendly…

5. Sherlock has another poolside meeting

In a clear callback to his first meeting with Moriarty in series 1’s The Great Game, Sherlock has another ominous encounter by a pool. But is it with Moriarty – or someone else?

6. An old character is returning

Lindsay Duncan’s MP Lady Elizabeth Smallwood, last seen being blackmailed by Charles Augustus Magnussen in series 3’s His Last Vow, is back – and she seems to have a job for Sherlock.

7. Sherlock has his own dodgy facial hair now

After teasing Watson for his moustache in the last series, Sherlock seems to have picked up some face fuzz for the new run of episodes. Has he been living rough?

8. Toby Jones has clearly been practicing his evil laugh

We don’t know much about the Marvellous actor's new villain, but he seems to be the main antagonist to John and Sherlock this time around based on his prominence in the new footage.

9. We may explore Mary’s secret past

Scenes in the trailer show Amanda Abbington’s former assassin in a headscarf and with brown hair, stalking a target – is this a flashback to her darker days, or a new adventure where she’ll have to embrace her old self?

10. Mrs Hudson and Mycroft fall out

“Get out of my house, you reptile.”

Good to know things are still sunny between Sherlock’s landlady and his brother…

11. And basically, it all looks very dark and exciting

Full of ominous music, gun battles, explosions and fistfights, this looks to be Sherlock’s most epic series to date. Frankly, we can’t wait to see what else they have in store.

Sherlock series 4 will air in early 2017