12 Monkeys ended its stellar Season 3 with an episode that changed our understanding of everything we thought we knew about the story so far. "The Witness" had plenty of action, but it was the emotional story beats of betrayal, redemption and sacrifice that made the episode soar. Now that our heroes know that Olivia is the key to everything, their mission in Season 4 seems fairly straightforward, though we've been told that there are no straight lines when it comes to time travel. Could saving Olivia from herself be the key? The killing people gambit never seems to pay off.