If you don’t play Assassin’s Creed, you might be a little confused as to what the upcoming movie is all about. We know from the trailers that Michael Fassbender plays Callum Lynch, who is a descendant of someone who lives during the Spanish Inquisition, and who is forced by Marion Cotillard to go back in time and relive his ancestor’s past as a gravity- and physics-defying assassin fighting against the Templar Knights. Now, with a new featurette, we’re able to delve deeper into the mythology of Assassin’s Creed to figure out exactly why these two groups are fighting.

The Templars and the Assassins have locked in a constant battle for supremacy throughout history, one obsessed with having power over the world and the other whose task is to free it. Guess which one is which. According to Fassbender in the video, “The Assassins are making sure that freedom is still protected and cherished.” So they’re guardians of free will with sick parkour moves, which sounds like a great concept for a video game, but will it translate onto the screen? Fassbender thinks so: “The concept of Assassins and Templars battling through the centuries is a fantastic cinematic experience.” And it’s true that even the trailers contain some really stunning visuals, like that Leap of Faith you can also see in the featurette.

Here’s the movie’s official synopsis:

Through a revolutionary technology that unlocks his genetic memories, Callum Lynch (Michael Fassbender) experiences the adventures of his ancestor, Aguilar, in 15th Century Spain. Callum discovers he is descended from a mysterious secret society, the Assassins, and amasses incredible knowledge and skills to take on the oppressive and powerful Templar organization in the present day.

Assassin’s Creed is directed by Justin Kurzel and opens in theaters December 21.