Sherlock series 4: Fans can 'expect tragedy' says showrunner Mark Gatiss

The BBC detective drama starring Benedict Cumberbatch returns next year

Martin Freeman and Benedict Cumberbatch as John Watson and Sherlock Holmes in Sherlock (BBC)

Fans hotly awaiting the return of BBC drama Sherlock have been warned to “expect tragedy” in series four.

Co-creator Mark Gatiss dropped some hints in a recent interview, after Steve Moffat similarly said the upcoming episodes starring Benedict Cumberbatch as the super sleuth would be “devastating”.

“Expect tragedy as well as adventure, that’s just how it goes,” Gatiss told Radio Times, adding that the TV show’s plotline would not necessarily follow that of Sir Arthur Conan Doyle’s original books.

“Just because it’s in the stories, doesn’t mean it’ll happen in the series,” he said. “There’s an awful lot of changes and an awful lot of places to go and things to do.

“It should be clear by now that while, of course, Doyle is our absolute god, we have gone quite a long way away as well. We’ve introduced Sherlock and Mycroft’s parents – I don’t think they’ve ever been seen in any adaptation – so there are lots of surprises to come.”

One character who could be facing the chop is John Watson’s wife Mary, played by Amanda Abbington, real-life partner of Watson actor Martin Freeman.

Dr John Watson and Mary Morstan get married in Sherlock (Hartswood Films/BBC)

Freeman has previously suggested that Mary could be killed off “at some point” in line with Conan Doyle’s stories.

“While we play fast and loose with the original stories, we generally follow the trajectory of what Conan Doyle did,” he told The Telegraph. “So [Watson] gets married and then Mary dies – so at some point presumably she’ll die.”

Should Mary face her demise in the next series, fans could see Watson move back into the Baker Street flat with Holmes, as happens in the books. But with Sherlock, anything could happen.

A one-off Sherlock special begins production in January for a possible Christmas broadcast while a further three episodes will be shot later in the year to be aired in 2016.