A villain is reportedly going to make a comeback in "Sherlock" season 4.

With filming already in progress, "Sherlock" season 4 is undeniably well on its way. While details about the upcoming series remain scarce, there are rumors that Moriarty will be resurrected next season.

Recent reports suggest that Moriarty was recently seen at the filming location of "Sherlock," igniting speculations that she will be back next season with more of her cagey acts.

Wales Online reported that the cast and crew of "Sherlock" were spotted filming in Tenby. As the filming drew crowds, a helicopter reportedly flew around St. Catherine's Island and passed by a Moriarty flag.

According to the report, the crowds thronged the island shores, hoping to catch a glimpse of what's rolling on the set. Some fans of the series were also there to see Benedict Cumberbatch, though it was unconfirmed whether the actor was filming on the set at the time.

Since "Sherlock" season 4 was confirmed, there have already been speculations about Moriarty's possible return in the series. While the network has not made any announcement about his return, fans speculate that actor Andrew Scott will reprise his role next season.

It may be recalled that earlier this 2016, co-creator Steven Moffat sat down to speak to TV journalist Boyd Hilton about what fans should expect of Moriarty in season 4.

"I think what we can say is we may or may not see more of Andrew Scott as Moriarty," he said.

Meanwhile, there are reports that season 4 will see Sherlock's encounter with his third brother, Sherrinford. Rumors have it that Tom Hiddleston is the one to play this role.

"Sherlock" season 4 is expected to premiere in January 2017.