Sherlock co-creator Steven Moffat has already said that series four "goes to a darker place than we've ever gone before". He's not wrong, if the latest promo picture for the BBC1 drama is anything to go by.
The new photo sees Benedict Cumberbatch's Sherlock staring challengingly into the camera. Martin Freeman's John Watson meanwhile, daughter Rosamund in his arms, looks distinctly unhappy about being a new Dad.
His wife Mary (Amanda Abbington) is at his side, but rather than looking lovingly down at their newborn, she is instead gazing across towards an anxious-looking Molly Hooper (Louise Brealey). Is that suspicion in her eye? Or perhaps conspiracy?
Mycroft (co-creator Mark Gatiss) is flicking his eyes down to his brother Sherlock, while Detective Inspector Lestrade (Rupert Graves) is slouching like an uninvited guest in the corner. Mrs Hudson (Una Stubbs) is looking with concern at John and his daughter.
It's all a far cry from the relatively carefree portrait that accompanied series three – and not just because Mycroft is looming over like the spectre at the feast.
But apart from the disconcerting glances across the room, what else can we learn from the new photo?
Well, there's a knife stuck through a sheaf of papers is on the mantlepiece – the same one that caught our eye in the last Sherlock promo image.
We argued then that it could be a nod to original Sherlock Holmes story The Adventure of the Musgrave Ritual – read why here.
Again, like the last photo, on the book shelf there appears to be an almost perfectly hidden reference to Doctor Who – a neat little trick by Moffat perhaps?
New to this photo is John's precious new daughter Rosamund Mary Watson, announced via an ad in the Telegraph last week.
Several people have pointed out how Watson always seems to be the one 'left holding the baby', as it were. While we're fully behind this display of modern parenting, we can't help being slightly concerned that Mary doesn't seem to be joining in.
Given that and Molly and Mary's uncomfortable stance in the new picture, we have a feeling they are going to be playing a more important role than ever in series four.
As last year's New Year special The Abominable Bride taught us, we underestimate the women in Sherlock's life at our peril.
Sherlock series four will begin on New Year's Day at 8.30pm on BBC1