Once upon a time, there was a lovely princess locked away in the highest room of the tallest tower of a castle guarded by a fire-breathing dragon.

She knew one day her true love would rescue her from this dreadful prison. But who knew her rescuer would be a big, green, ornery ogre named Shrek. Her true love? No way.

“But you shouldn’t judge a book by its cover,” said Marion Bienvenu. “You never know when he might be your true love.”

Bienvenu plays the imprisoned Princess Fiona in Playmakers of Baton Rouge’s production of “Shrek the Musical,” which opens Friday, June 5, in the Reilly Theatre at LSU.

The show is based on the 2001 DreamWorks animated film, which brought William Steig’s 1990 children’s book to the big screen, featuring the voices of Mike Myers, Eddie Murphy and Cameron Diaz. The musical made its Broadway debut in 2008.

“The Broadway show ran almost three hours, but ours runs an hour and 45 minutes,” said director Addie Barnhart. “I think we’ve done a great job in paring it down yet keeping all the best stuff in it to tell the story. And the script we’re using is closest to the movie, so you will be seeing the Shrek you know.”

Playmakers veteran Wil Thomas is taking on the role of the aforementioned ogre, whose solitude in the swamp is disrupted by a swarm of fairy tale characters — Pinocchio, the Three Bears, the Three Little Pigs, Peter Pan, the Big Bad Wolf and the Mad Hatter among them.

It seems they’ve been banished from the Kingdom of Duloc by Lord Farquaad, who promised to put them to death if they ever returned.

Freaks, he called them, undesirables not fit to live in his kingdom. Shrek isn’t concerned about their differences but their noise level. They’re driving him nuts, so he asks Farquaad to take the fairy tale characters back into the kingdom. Farquaad strikes a deal: If Shrek can rescue and bring him Princess Fiona, Farquaad will give the ogre the deed to the swamp.

So the adventure begins with Shrek accompanied by a talkative donkey on the castle trail.

In the film, comedian Eddie Murphy’s timing and wit made the donkey the film’s most popular character. In Playmakers’ production, 13-year-old Myrik Mitchell is striving to carry on Murphy’s tradition.

“He’s very humorous, and the character fits me perfectly,” said Mitchell. “But he also requires a lot of energy. His character takes a lot out of me at the end of the day.

Add to that the furry donkey costume, and Mitchell is carrying a load both mentally and physically. But he’s not complaining.

“It’s fun,” he said. “I see the donkey as a child at heart. He’s completely innocent, because he doesn’t want or try to hurt anybody. He’s always trying to be funny.”

And the donkey succeeds, making light of Shrek’s perpetually bad mood while proving himself a true friend on every step to Fiona’s castle. Little do they know, Fiona harbors her own secret.

The donkey stumbles upon the secret by mistake but agrees to keep quiet. Fans of the film will already know it, but there are no spoilers here for those new to the story.

Still, Bienvenu provides a hint. “We’ll have another actress for that when the time comes,” she said.

Otherwise, Bienvenu is the princess and says the part is perfect for her.

“I’ve always wanted to play a princess, but I knew that if I ever did, that princess would have to be off kilter,” she said. “I’m the unconventional type, so Fiona’s perfect.”

Fiona starts off prim and proper, then she lets loose, Bienvenu said. “She likes to have fun. And there’s the scene with the fart and burp.”