Sherlock Series 4 Could Be The Show's Final Series

Fans are eagerly anticipating the long-awaited fourth series of BBC One's Sherlock, but creator Steven Moffat warns that this could be the last go-round for Sherlock Holmes and John Watson. Lead actor Benedict Cumberbatch's has risen to international stardom and is set to star as Marvel's Sorcerer Supreme in Doctor Strange this year but returned to Sherlock out of a sense of loyalty to the fans of his breakout role.

Moffat said he was "amazed" that the network was able to bring Cumberbatch and co-star Martin Freeman, whom Moffat now considers "film stars," back for another three-episode TV series, and he's not sure if they'll be able to repeat that trick again. ""I don't know how long we can keep it going," Moffat told the Telegraph. "I'm personally willing but I'm hardly the main draw. I would be moderately surprised if this was the last time we ever made this show. But it absolutely could be."

It's not hard to figure out why the BBC made the extra effort to draw Cumberbatch and Freeman back for another series. Sherlock is one of the BBC's most watched shows and was nominated just yesterday for six Emmy Awards.

Given that Cumberbatch is now an Oscar-nominated performer, and that Freeman starred in The Hobbit trilogy, Moffat says it should be clear that the two stars aren't doing Sherlock for the money.

"We do have two film stars in the programme," Moffat says. "They haven't needed to do these jobs for a very long time. They're coming back because they want to. I'm amazed that we've got this far. I thought that once they had become extremely successful, we would only get to do one more series. There's never going to come a time when we do a longer run, because this is what the series has become. It's an occasional treat where you get three movies. It's how it works."

In the meantime, work continues on Sherlock Series 4. While Moffat was coy about plot details, he did say that they were diving deep into the works of Sherlock Holmes' creator, Arthur Conan Doyle, for the new series.

"There are stories that we are making use of in different ways," Moffat said. "We're using stories that people don't know so much. Now we are getting into equally good, but far less well known, Conan Doyle stories."

Sherlock Series 4 is expected to air in 2017.