Watch: Miranda Otto, Brian Cox voice 'Lord of the Rings' animated prequel

Aug. 22 (UPI) -- Warner Bros. released the trailer for the film The Lord of the Rings: The War of the Rohirrim on Thursday. The animated film opens Dec. 13.

Miranda Otto reprises her role as the voice of Eowyn, telling the story. The War of the Rohirrim is set 200 years before the Oscar-winning Lord of the Rings live-action films.

Brian Cox voices Helm Hammerhand, the king of Rohan after whom Helm's Deep was named. Helm's Deep was the setting of the climactic battle in The Lord of the Rings: The Two Towers.

Helm's daughter, Hera (Gaia Wise), refuses the marriage proposal of Wulf (Luke Pasqaliano). When Wulf's father confronts Helm, he kills him in a fight, starting the war.

Peter Jackson executive produces the animated film from director Kenji Kamiyama, based on material from J.R.R. Tolkien 's books.

Season 2 of The Lord of the Rings: The Rings of Power premieres Aug. 29 on Prime Video. Another live-action Lord of the Rings film is in production for a 2026 release.