What to Know About ‘The Lord of the Rings: The War of the Rohirrim’

If you would like to know who the Helm of Helm’s Deep is, you are in the right place.

Also, if you are an anime fan who has never watched a single “Lord of the Rings” film, welcome.

A new Warner Bros. animated adventure, “The Lord of the Rings: The War of the Rohirrim,” is in theaters, the latest installment in a franchise of seven — soon to be eight — movies based on the novels of J.R.R. Tolkien. Set roughly 200 years before the events of the “Lord of the Rings” trilogy, it tells the tale of a storied king’s quest to defend his land from an invading army.

Here’s what to know about where the story came from, how it fits in with the rest of the “Lord of the Rings” universe and which familiar characters you might find.

Did Tolkien write this story?

The characters in the film, directed by Kenji Kamiyama, are based on details in the appendices at the end of the “Lord of the Rings” novels. They cover the history of the rulers of Rohan, the fictional kingdom in Middle-earth known for its horse-tamers and riders.

Obviously, turning footnotes into an animated film required some rewriting and fleshing out — the filmmakers’ task was essentially to bring a family tree to the screen, which includes Helm Hammerhand, a legendary king of Rohan; his sons, Haleth and Háma; and an unnamed daughter. The producers chose to focus on Helm’s daughter, whom they called Héra for the film. (Tolkien left her fate unclear.)