The official trailer for Transformers One has just been released, giving fans a first look at the next film in the saga, in which director Josh Cooley provides context to the backstory and previous friendship between the beloved Megatron and Optimus Prime characters.

“We’ve only known them as villains and/or the rivalry between these two characters,” Cooley told Blavity’s Shadow and Act. “The thing that got me interested about this film from Day 1 was the fact that it’s the beginning of their friendship or the beginning of their relationship, and we get to see how they weren’t always enemies.”

He added, “They were like brothers, and then we see that relationship fall apart. For me, the big part of the story is seeing how these two characters that we know… we see why and how they became who they are.”

The film also offers a glimpse into their home planet, Cybertron, further explaining why they are the way they are. It is also the first time a movie in the Transformers franchise does not include humans.

Here’s the official description:

TRANSFORMERS ONE is the untold origin story of Optimus Prime and Megatron, better known as sworn enemies, but once were friends bonded like brothers who changed the fate of Cybertron forever.

It is the first-ever fully CG-animated Transformers movie. 

“The entire thing is on their planet, Cybertron, it’s all about the Transformers. All about the characters we know and love,” Cooley said of how this film is unlike the rest. “We’ve taken humans out of the equation, and it’s just about our characters. We get to see what it’s like for Transformers, on their world, on their planet. When I first started at Hasbro, they gave me this kind of library of the entire timeline of Transformers, which is way bigger than I ever knew. It’s very token-esque, and to be able to go back earlier than anything that’s ever been told before on-screen was exciting.”

Cooley’s most defining lesson working as the director of this film is his North Star since the beginning of the project. That is the nuances and initial dynamic of Megatron and Optimus Prime.

“I just had a feeling that this was going to be my North Star for this film, and it was, which is that the relationship between the two of them is just that no matter what,” he explained. “This has the scale and the epic-ness of any Transformers film. It has the action and all the adventure, and we added an element of comedy, which you see a lot of in the trailer. The movie has real stakes to it that we’ll see later, but the biggest thing was about the relationship between the two of them. None of that other stuff would work unless we had that relationship kind of underlying throughout the entire film, and I’m very proud of that.”

“I think we did a really good job of keeping that true and the audience invested in that,” Cooley continued. “My goal from Day 1 was I want people to feel for these characters, even though they’re robots and these aliens on another planet. I want audiences to continue, or actually not just continue to, but to feel from them differently and take them to heart.”

Cooley revealed his most memorable scene to shoot, which features what he called a stellar performance by Brian Tyree Henry.

“When we recorded it, I realized we had something really good,” he recalled. “We see them go from friends to enemies, and so at a certain point, this relationship has to start to fall apart, and there’s this one pivotal scene where that starts to happen, and Brian, just his performance was so gripping, and I just sat back and just let him go, and it was amazing to watch. It was one of the best recording sessions I’ve ever been in.”

Transformers One hits theaters Sept. 20, also starring Chris Hemsworth (Orion Pax), Scarlett Johansson (Elita-1) and Keegan-Michael Key (B-127), Steve Buscemi, with Laurence Fishburne and Jon Hamm.