The BBC's Sherlock is coming back on January 1st, but the detective is already making his way back to London in a seven-minute mini-episode just released online. "Many Happy Returns" doesn't give us the homecoming we'll see in "The Empty Hearse" next month, but it hints that Sherlock's been busy in the rest of the world — and that Anderson, the forensic scientist who spent most of the past two seasons hating him, is starting to put the pieces together. For the occasion, the BBC has also added a new blog post from "John Watson," who's ostensibly signing off forever in order to move on after Sherlock's death. The mini-episode format is one that Sherlock showrunner Steven Moffat also played with before the 50th anniversary of Doctor Who, shooting short prequels that helped explain some of the episode's more dramatic developments.