Each Middle Earth film has kicked off with a brilliant scene setter that serves as a prologue to the main action; the history of the One Ring, Gandalf's fall from a new perspective, the origins of Gollum, the tale of the Lonely Mountain and Gandalf convincing Thorin to reclaim Erebor are all highlights of their respective films. It'd be troll-level logic to think Jackson wouldn't keep up the tradition for Battle. But what will it be about? Our guess would be a scene that's been teased since the very first trailer. Back from when The Hobbit was just two films, the teaser for An Unexpected Journey (which then would end after the barrel sequence) had a shot of Gandalf amongst some ruins being attacked by an white-skinned assailant. A cheeky bit of freeze framing reveals the attacker is none other than Thrain, Thorin's father, played in the films by Mike Mizrahi. As, in the books at least, Thrain is dead by the time the company of Dwarves began their journey this has to be a flashback, so, it'd make a good starting part for the third film. From the decor it seems we're at Dol Guldur, making this a moment referenced in the Return Of The King appendices were Gandalf, investigating the abandoned fortress, finds the former King totally deranged. It culminates in Thrain giving him the map and key that have proven so essential in the films, essentially setting in motion the whole series of events. Of course the scene could easily be cut and left for the Extended Edition like Bilbo's excursions in Rivendell. But until we get a proper answer it'll have to do.