Transformers: The Last Knight, the latest in the Hasbro franchise, has been in production for a while, but Michael Bay and co. have mostly kept all plot details under wraps. One rumor made its way to the surface a few months ago, but it wasn't until today that it was pretty much confirmed. This could get a little spoiler-y, so proceed at your own risk.

According to a video posted to Michael Bay’s Instagram, the crew is shooting on location somewhere in the Scottish highlands. “Scotland,” “here,” and “mountains” can be barely heard over the wind and roar of a huge helicopter hovering onscreen behind Bay’s head, with sweeping romantic vistas of mountainous green all around them.

Why is this important? Well, there was a rumor going around, reported first by JoBlo, that The Last Knight would have something to do with the King Arthur legend. Optimus Prime would head back to his home planet Cybertron only to discover that it’s a ruined mess, and he needs some sort of artifact to help being the dead planet back to life. Where is this artifact? Earth, of course! And who does this artifact somehow have ties to? Merlin, the wily wizard who helped Arthur become king of the Britons and advised him during his rule. What, exactly, is this artifact? If this official image from the film is any clue, the legendary sword Excalibur would be a good bet. And the best place to find anything having to do with King Arthur is Great Britain, of course.

BBC also grabbed some photos of the set where actors can be seen wearing medieval clothes and riding horses. It could be some kind of flashback sequence, or we could see the Autobots traveling back to the time of trebuchets and tyrants, with Bumblebee trying to disguise himself as a chrome-and-yellow horse.

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