Leave it to "Sherlock" to release a trailer loaded with twisty reveals that require just a bit of work from loyal viewers. BBC One has released an interactive trailer for the show (which returns to the air Jan. 19 at 10:00 p.m. ET on PBS in the U.S.). Click on the text that pops up intermittently throughout the trailer and see additional photos, additional footage, and even a hint as to how Sherlock may have survived that fall after all (think diagrams). 

What also learn from the trailer that an act of terrorism against London is in the works, and it appears to be an airborne agent, plus Sherlock is going to be walking in on Watson a full two years after his so-called death -- and well after he's moved on with his life and even left Baker Street. But then, you'll want to watch the trailer (and all of the additional info) to see that for yourself. 

Watch the clip from "Sherlock"'s season three below: