The last of four offerings in Opera Theatre of St. Louis’ 43rd festival season is a Janus-like realization of Christoph Willibald Gluck’s masterwork, Orfeo and Euridice, serious initially then gathering steam toward a conclusion as radical as it is rousing.

While the first half of the show is a near model of decorum and serenity, the second half, once rolling, is by the finale a theatrical riot sparkling with grunge and glitter and touched with reflections of the Metropolitan Museum’s recent religio-centric (and quite vulgar) gala.

(Wednesday evening’s performance was de facto the opening night for this Orfeo. On Saturday, a medical emergency during intermission prompted the company’s administration to wisely, and compassionately, call off the second half of the show.)

The Orpheus myth, like most myths, is potent with metaphor, but in itself thin and preposterous, so perhaps a wise audience member should be content to sit still and see what happens on the stage as the story unfolds.

What happens is Orfeo and Euridice, a blissfully married couple whose love, as we shall see, knows no bounds.

Euridice dies and goes to the underworld. Thanks to Amore, goddess of love that she is, Orfeo wiggles his way into the underworld, where he is permitted to rescue Euridice if, and only if, he follows one unbreakable rule.

He breaks it; Amore has to set things on track again. The couple is rapturous and returns to the world barely worse off for the traumas they have had inflicted upon them.

Their return sets off a celebration by their once-grief stricken friends that by any standard was over the top. But because the music is so alluring, and because the music and much of the dancing were performed with such grace and transcendent beauty, and because the singing by the three principals (Jennifer Johnson Cano, Orfeo; Maria Valdes, Amore; and Andriana Chuchman, Euridice) is so magnificent, it really doesn’t matter what stage directors and scenic designers and costumiers bring to a crown jewel such as Orfeo.

But get this. It is possible that Maestro Gluck and his accomplice, the librettist Ranieri de Calzabigi, might not regard this production with the dismay experienced Wednesday by a stuffy 21st-century septuagenarian writer.

Wikipedia gives a substantial account of Orfeo and Euridice, and its place in the history of opera, and its role, in the 18th century, in changing the course of opera from opera seria— serious opera—to the form more recognizable to us today as “opera.”

Orfeo ed Euridice, Wiki says, is the first of Gluck's "reform" operas, in which he attempted to replace the abstruse plots and overly complex music of opera seria with a "noble simplicity" in both the music and the drama.

The opera is the most popular of Gluck's works and was one of the most influential on subsequent German operas. Variations on its plot—the underground rescue-mission in which the hero must control, or conceal, his emotions—can be found in Mozart's The Magic Flute, Beethoven's Fidelio, and Wagner's Das Rheingold.

So in the big scheme of artistic things, perhaps Opera Theatre’s brazen production is a natural, legitimate descendant of Maestro Gluck’s pushing opera into a more comprehensible, more contemporary form. Perhaps.

This Orfeo represents risky business in its rambunctious poke in the eye of tradition. While some might say “Get serious,” others will cheer such a fresh and irreverent adventure, a production at once noble and outrageous in a topsy-turvy world, a world as frightening and fragile as we have ever seen, a haven for a couple of hours before heading out into miasmas, natural and person-made.