“Every great cause has martyrs,” Cumberbatch’s Holmes says in the trailer. “Every war has suicide missions, and make no mistake: this is war.”
The trailer also shows the two detectives walking down crowded 19th-century England streets, running through foggy and dark alleys, discussing ghosts from their pasts and Watson becoming angry at Sherlock’s refusal to wear the deerstalker hat.
Steven Moffat, the show’s co-creator, previously confirmed that the upcoming special will be independent of the hotly anticipated fourth season.
“The special is its own thing,” Moffat said. “We wouldn’t have done the story we’re doing, and the way we’re doing it, if we didn’t have this special. It’s not part of the run of three episodes.”
A first-look clip shown at Comic-Con in July had Holmes, Watson and Baker Street landlady Mrs. Hudson arguing about their roles in Watson’s books and why Watson had to grow the mustache.
Fans of the show have been rabid for the fourth season, likely to air in early 2016. Moffat assured them that there is a plan in place for the new episodes that might make viewers emotional.
“We have a plan…we practically reduced our cast to tears by telling them about the plan,” Moffat said.