The trailer, which debuted Sunday, doesn't reveal much about plot. But we do learn that Watson has grown a mustache as part of his post-Holmes recovery.
“I don’t care how you faked it. I want to know why," Watson tells him in the trailer.
Sherlock's third season airs New Year's Day across the pond, but American viewers will have to wait until it airs January 19 on PBS. A mini-episode will also air Christmas Day in the U.K.
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