Sherlock producer Steven Moffat spoke at Comic-Con recently to preview the upcoming special and fourth season.
Moffat, who is the co-creator of Sherlock, spoke with Digital Spy in a new interview. He was also joined by Rupert Graves, who plays D.I. Lestrade in the series.
Moffat was asked about the mode of producing a new season every two years and while he said this wasn't the initial plan for Sherlock, he commended how well it works out for them.
"It was never the plan for it to be at a unique rate of delivery but I don't think it hurts - it's interesting that starvation works as well as it does," Moffat said.
Moffat and Graves also discussed the upcoming special, which takes place in Victorian England. Graves spoke on the "quiff-sized mutton chops" he'll be wearing in the special.
As for season 4, Moffat did not tease much but he did reveal that there was some darkness ahead for Sherlock (Benedict Cumberbatch) and Watson (Martin Freeman).
"We've got a clear idea what we're gonna do and it's gonna be another shift in tone and yes there's gonna be some dark stuff coming but there always is," he explained. "There'll also be loads of fun and jokes and detection and all that nonsense."
The Victorian special of Sherlock is slated to air in the winter holiday season while season 4 won't even be filmed until early 2016.