When Alan Menken — the songwriting virtuoso behind Disney’s late 20th century animation renaissance — was brought in to score an adaptation of “Hercules,” he assumed a classic story would call for some classic music to match.

Instead, the directors of the 1997 film wanted gospel.

“I said, ‘Really? Explain this to me, please,’” Mr. Menken recalled in a phone interview. Hercules’ epic journey to prove he’s a hero involves quite a few Greek gods — and gospel, they explained, is the music of praying to God. “I go, ‘Well, that’s a stretch. But O.K. Let’s play with it.’”

The resulting score became a cherished chapter in the Disney songbook. Now the songs are coming to life in a world premiere stage adaptation — and Mr. Menken, along with lyricist David Zippel, is adding five more.

But in a turn from Disney’s typical theatrical adaptations — commercial endeavors aimed at Broadway — “Hercules” will be presented for free in a weeklong run at the Delacorte Theater in Central Park beginning Aug. 31.