Brian Cox Lends His Voice to a King in Lord of the Rings: The War of the Rohirrim First Look (Exclusive)

Brian Cox is venturing into Middle-earth, newly envisioned as an anime.

On Tuesday, June 11, New Line Cinema and Warner Bros. shared an exclusive first look at its upcoming movie The Lord of the Rings: The War of the Rohirrim, an anime-style feature film set more than 150 years before the original Lord of the Rings trilogy.

The first-look images show Cox's character Helm Hammerhand sitting alongside members of his family, including the newly introduced characters Héra (Gaia Wise), Haleth and Hama. Another up-close image of Héra shows her holding a sword.

"There are certain things I don't think we could have necessarily done — or they would have made it extremely expensive — elements to the storytelling that you could do in anime in a way that was kind of breathtaking, actually," Philippa Boyens, a producer on the movie who also cowrote the screenplays for each of the three Lord of the Rings movies and The Hobbit trilogy, tells PEOPLE of bringing Middle-earth to the popular Japanese animation style with director Kenji Kamiyama.

Cox lends his voice to the movie's lead character, Hammerhand, described as "the legendary King of Rohan" in an official synopsis for the film. The movie depicts a conflict between Rohan, a kingdom featured in the original movie trilogy, and the Dunleding that forces Helm and his kingdom to take refuge in a fortress dedicated fans will recognize as Helm's Deep.

"There's some pretty powerful moments in this film, but just the way in which Brian could just so effortlessly reach for them was wonderful," Boyens, 62, says of Cox's voice performance in the movie.

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A synopsis for the movie reads that Helm's daughter Héra "must summon the will to lead the resistance against a deadly enemy intent on their total destruction" as Rohan's situation grows more perilous. "I have to say, [Cox] being the father of a daughter also was really interesting given the dynamic at the heart of this film," Boyens adds of the Succession alum's performance. "That was really great."

Joining Cox and Wise in the movie's voice cast are Luke Pasqualino, Lorraine Ashbourne, Benjamin Wainwright, Laurence Ubong Williams, Shaun Dooley, Michael Wildman, Jude Akuwudike, Bilal Hasna and Janine Duvitski. Miranda Otto, who memorably played the character Éowyn in Peter Jackson's Lord of the Rings films, reprises that role as a narrator throughout the new movie as well.

"I think it took her maybe about 10, 15 minutes standing at the microphone and you could feel the voice coming back and the character coming back," Boyens says of Otto's performance. "It was incredibly wonderful to watch," 

The Lord of the Rings: The War of the Rohirrim releases in theaters Dec. 13.