Today at Star Wars Celebration in London, Star Wars: Episode VIII director Rian Johnson shared some new details on the 2017 movie as well as his own experience making it.

“It was an incredible experience on many different levels,” Johnson, as reported by Entertainment Weekly. “You come into it with nostalgic feelings, but your job is to get beyond that very quickly. The ultimate responsibility is to sit in front of Mark [Hamill], sit in front of Luke Skywalker … and then get to know Mark as an actor and start working on a script and get back to the work of filmmaking.”

Johnson also shared that Episode VIII will be the movie where “we start zooming in on the characters and getting to the heart of them, challenging them, and pushing them deeper.”

This matches up with what Poe Dameron actor Oscar Isaac said in May.

“In the new film, there’s a lot more to do. What happens now is the heroes get tested. All three of them get tested immensely,” he explained at the time, adding the film is “dark,” but “not really dark.”

Also at the Star Wars Celebration panel, Johnson confirmed Episode VIII will pick up directly after The Force Awakens. “That final scene in VII, I want to see what happens next,” he said.

Co-stars Daisy Ridley and John Boyega have also spoken about the film’s darker tone. “It’s a different take–darker, bigger,” Boyega told Variety. “Someone will say: ‘How do you get bigger than Force Awakens?’ But it’s crazy.”

Star Wars Episode VIII arrives in theaters on December 15, 2017. It also stars Adam Driver, Laura Dern, Domhnall Gleeson, Carrie Fisher, Anthony Daniels, Gwendoline Christie, and Andy Serkis.