A friend suggested during a dinner party that Roger Baum -- the great-grandson of "Wizard of Oz" creator L. Frank Baum -- should write a book based on the characters who live in the Land of Oz.

Roger Baum got past his initial misgivings and wrote "Dorothy of Oz" in 1989. It’s taken 25 years, but a film version of the book, the animated "Legends of Oz: Dorothy’s Return," opens today (review, D6).

"My initial reaction was a presumption that I could do it. Then I began to wonder if I could really do it. There are millions of Oz fans worldwide. My great-granddad’s books have been translated into 72 different languages. I didn’t want to insult my great-granddad, but I think it worked out OK," the 75-year-old Baum says.

Fans of the Oz books will see familiar faces -- Dorothy and Toto -- but also new characters such as the wicked Jester (voiced by Martin Short), the heroic Marshal Mallow (Hugh Dancy), the wobbly owl Wiser (Oliver Platt) and the ancient tree Tugg (Patrick Stewart). Baum’s plan was to use the original characters from his grandfather’s books to bridge his works to the original tales, but he then add new characters and events even if they didn’t line up exactly with the original books.

"My great-granddad wrote 14 books and he never meant for them to be a series. But the kids kept asking for another one," Baum says. "Some of his books are contradictory. So I thought it was safer to add new characters. I also kept that all of the stories are about love, heart, wisdom and courage."

The adaptation of "Dorothy of Oz" to script form, by Adam Balsam and Randi Barnes, included several changes. They move the scenes of Dorothy in Kansas to a more modern time and have the evil Jester turn the people of Oz into marionettes instead of china dolls.

Baum had final script approval, but he was very cautious about suggesting changes to the early pages.

"You can change one thing at the beginning and it has a ripple effect. I found myself concentrating on the ending because those were simple to maneuver and change. The important thing was that good wins over evil," Baum says.

He understands why so many people love the books his great-grandfather wrote because his parents read him the books every night.

L. Frank Baum died 19 years before Roger Baum was born, but he heard lots of stories about his great-grandfather.

"I hope this is a compliment to my great-granddad," Baum says. "It was a scary proposition but also my honor."