Sherlock's new season debuts in the U.K. on New Year's Day and in the United States on January 19, but in the meantime, there's this mini-episode. "Many Happy Returns" helps lay some of the groundwork for how Sherlock is going to come back from the dead — well, from the seemingly dead. The guy's brilliant, but he's not immortal. "Don't worry, I'm going to be with you again very soon," he says in an ominous video greeting to his bereft companion. Man, not soon enough.