On Tuesday, the drama at St. Paul’s Ordway Center began well before the curtain opened for “Miss Saigon,” the controversial blockbuster musical by the creative team behind “Les Misérables.”

Outside the theater, over 100 Asian-American activists and their multi-ethnic allies demonstrated against the production. The group handed out fliers and urged patrons to boycott a show that they said promotes racism, sexual trafficking of minors and pernicious stereotypes. The start of the show was delayed for 10 minutes.

Inside the theater, the production’s opening scene, set in a nightclub during the Vietnam war, seemed to bear out their complaints. Called “The Heat Is On in Saigon,” it involves American G.I.s bidding on gyrating, scantily-clad Asian women.

But Fred Hanson’s stylish, sex-soaked staging had other issues. “Miss Saigon” had an uneven sound mix in the first act, with the orchestra often overpowering the singers. The production got better and clearer in the second half, evening out and becoming more nuanced, even if the narrative remains one where Asia becomes the backdrop for an old Western story.

The creative team of composer Claude-Michel Schonberg and lyricists Richard Maltby, Jr. and Alain Boublil transposed Puccini’s “Madam Butterfly” to Southeast Asia in the 1970s. “Miss Saigon,” so named because of a prostitution pageant put on by a pimp named The Engineer (Orville Mendoza), centers on an American G.I., Chris (Charlie Brady), and a 17-year-old Vietnamese virgin, Kim (Manna Nichols), who has been pressed into prostitution.

Chris’s friend John (Nkrumah Gatling) buys Kim for him. The two fall for each other and have a quickie traditional marriage. The war intervenes and separates them. Chris goes home, unaware of that she is alive and carrying his child. He marries an American girl, Ellen (Maggie Cansler).

Eventually, Chris gets word that he is father to a son. Chris, John and Ellen go to Bangkok, where Kim and The Engineer have fled. It’s not a happy reunion.

Critic Michael Feingold called “Miss Saigon” a “kitsch tragedy of the betrayed geisha and her feckless American lover.” But the show, whose 25th anniversary comes up next year, has proved critic-proof. Audiences have swooned to its performances, even if the music is not particularly memorable, save for “The American Dream.” “Saigon” also has bits that seemed plucked from other shows by the creative team (The Engineer and Thenadier in “Les Miz.” are close relations).

Still, there are reasons for its enduring popularity. It has a grand, almost cinematic scenic design (courtesy of designer Michael Ananaia), complicated staging that includes the landing of a helicopter, and Baayork Lee’s fetching choreography.

The Ordway cast is very strong. Nichols brings a sweet spirit to Kim, and she draws our sympathy immediately. Brady invests Charlie with muscularity and feelings.

Mendoza is the best player in the cast. He mines The Engineer for laughs, presenting a pimp who is a dreamer trapped in terrible circumstances.

Gatling comes in a close second to Mendoza. His John delivers one of the highlights of the night in a complicated show that drew a sustained standing ovation.