"Sherlock" is all set to return to your TV screens with season 4 in January 2017 as the production wrapped up on August 5. Although there are hardly any spoilers out there, guesswork is in full swing, thanks to the three keywords revealed by the producers.

According to reports, the three keywords are Thatcher, Smith, and Sherrinford. It has led many to speculate that it indicates a Sherlock Holmes- Irene Adler reunion. The revelation was made by executive producer Sue Vertue, showrunner-writer Steven Moffat and writer-actor Mark Gatiss at the San Diego Comic-Con. Ever since the revelations, it is being said that season 4 is most likely to revolve around these three characters.

Though Margaret Thatcher is not possibly the case featuring in season 4, the keyword might refer to an old case called "The Six Thatchers." John Watson also talked about it on his blog. Notably, the case featured in season 2 and saw Holmes losing Adler from execution. Now, it is unlikely that the appearance of Adler and the case in the said episode was a coincidence and thus, chances are high that it is a pointer towards the coming reunion in season 4.

In the meantime, Benedict Cumberbatch has said that the fourth season might be his swan song and his future on the show remains uncertain. The actor even said that the series could end with the coming season. Though he expressed a desire to continue portraying the titular role of the detective, he clarified that whatever is good for the show should be implemented even if it means putting an end to it.

In other news, it is being said that season 5 might not see the light of the day because of the busy schedule of the actors, including Cumberbatch. He has landed with Marvel's "Dr. Strange" role and will be essaying the lead role in the movie. He has some more projects too. Same is the case with Martin Freeman aka Dr. John Watson. He is also into Marvel Cinematic Universe. Steve Moffat and Mark Gatiss (who plays Sherlock's elder brother Mycroft Holmes) are also working on different projects.