Fans still mourning the end of Kathryn Lasky’s 15-book Guardians of Ga’Hoole series, which came to a close in 2008, will have a chance to reunite with Soren the barn owl when Legend of the Guardians: The Owls of Ga’Hoole (Warner Bros.) arrives in theaters on September 24. Directed by Zack Snyder (Watchmen; 300), the CGI animated film is based on the first three books in the series: The Capture, The Journey, and The Rescue, and will be released in 3D and IMAX.

Although some of the books Lasky wrote for the Dear America series have been made into TV movies, this was the first time one of her books has been made into a feature film. “The first word that comes to mind is slow,” she says of the experience (the series was optioned in 2005). “But it’s been very positive. They’ve consulted with me consistently throughout the five years, and I feel like that they have remained very faithful to the spirit of the books and the characters. That was what was most important to me.”

The role of Soren is voiced by Jim Sturgess (The Other Boleyn Girl); Helen Mirren, Geoffrey Rush, Abbie Cornish, Emilie de Ravin, Hugo Weaving, and Ryan Kwanten also contribute speaking roles. Scholastic has published a movie tie-in edition of the first book in the series, and Shadow Wolf, the second book in Lasky’s Wolves of the Beyond series (which is also set in Ga’Hoole), is due in October.

Lasky had a chance to see a rough cut of the film last month, and was impressed both by the characters’ voices—“I think as an author you always hear voices in your head, and to me they sound very authentic,” she says—and the animation. “Soren’s younger sister Eglantine is just adorable. I thought, Why didn’t I make her cuter [in the books]? I know this sounds weird, but they added eyelashes to her. Anatomically speaking, that’s probably not correct, and not all of the owls [have them]. But Eglantine does, and the result is irresistible. My husband went with me and we think she looks like our granddaughter. It was fabulous to revisit these characters.”

Lasky and her family will attend a premiere of the film in Los Angeles next month, and on September 25, the day after the movie’s wide release, she will do a reading in Boston as part of a private screening and party tied in to UNICEF’s Trick-or-Treat for UNICEF campaign, which is marking its 60th year (Lasky is a board member). The author is now working on the as-yet-untitled third book in the Wolves of Beyond series, as well as a historical mystery for adults, which she says she will likely publish under a pseudonym. There are currently more than five million copies of the Guardians of Ga’Hoole series in print.