The battle of Helm's Deep is a true highlight of The Lord of the Rings, riveting readers and movie audiences alike as the people of Rohan stand strong against an invading army of orcs. The upcoming anime prequel film The War of the Rohirrim (in theaters Dec. 13) will portray a similar combination of epic action and intense drama in its story of Helm Hammerhand (voiced by Brian Cox), the ancient king of Rohan, for whom the fortress is named. He didn't get that powerful name for nothing, and director Kenji Kamiyama was eager to depict the story's hard-hitting action.

“I knew that recreating the cavalry battles of Rohan would be difficult, whether in live-action or animation,” Kamiyama tells Entertainment Weekly. “But I thought it would be amazing if I could pull it off, so I took the challenge. There were so many scenes I wanted to depict, such as King Helm beating his enemies with his fists, and of the warriors fighting with their swords.”

Kamiyama continues, "King Helm was definitely the most challenging character to design, but also was very rewarding. Because he’s the strongest king, we needed to make sure he embodied both strength and dignity."

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In expanding the king’s story from J.R.R. Tolkien’s appendices to The Lord of the Rings, screenwriter Phoebe Gittins and producer Philippa Boyens (who cowrote director Peter Jackson’s live-action film adaptations) fleshed out the character of Helm’s daughter. Originally unnamed by Tolkien, here she’s known as Hèra (Gaia Wise). Perfectly capable of wielding a sword, Hèra also seeks other solutions to problems.

“This story is of her defending her people and ensuring their survival by putting their needs above hers, and bringing this complex emotion to a very male-dominated world,” says Wise. “She finds these fantastic ways out of issues because she doesn’t have that sort of brute strength. She uses her mind.”

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Rohan is invaded by neighboring Dunland and its leader, Wulf (Luke Pasqualino), who makes an interesting nemesis not just for Helm but also for Hèra, whom he’s known for years.

“Her interactions with him are about how someone from your childhood can change so drastically,” Wise says. “She then has to make some of the hardest decisions that she will ever make, in order to ensure the survival of her people.”

A version of this story appears in EW's complimentary Comic-Con 2024 Preview print edition, being passed out in San Diego throughout the convention.