I anticipated sitting through no more than a half-hour of Ragnar Kjartansson's 12-hour Mozart marathon, Bliss, a Performa 11 commission presented at New York's Abrons Arts Center on Saturday, Nov. 19. Kjartansson is a fascinating artist, but as described by the advance press material, "Bliss" sounded like a nightmare. The production is a full staging (including sets and costumes) of Mozart's 1786 opera The Marriage of Figaro, but cast and orchestra continuously repeat from noon until midnight a less than three-minute excerpt from an aria in the opera's final scene. Audience members were invited to come and go as they pleased.

Yet after more than two hours riveted by the piece, I finally staggered out of the theater into the night feeling a bit stoned. Had I drunk the Kool-Aid? After I'd collected myself, Bliss stuck—it was entirely engaging and revelatory as all the best art ought to be. If it ever comes to a theater near you, don't miss it!

The Icelandic artist, 35, makes maniacal duration pieces. Take for instance The End, his work for the 2009 Venice Biennale, where he represented Iceland and occupied the gallery space for the entire months-long run of the show. Each day, he painted a funky portrait of a sexy male friend in a Speedo bathing suit, as visitors ogled. In comparison with the similarly ambitious, but more seriously high-brow efforts of performance-art diva Marina Abramovic, Kjartansson's approach is laid-back. But his work is no less demanding on the artist, performers and audience.

It took about a half-hour to fall into the rabbit hole Kjartansson set up in Bliss. First, there was the silly novelty of it all. The elaborate but crudely hand-painted set—depicting a garden scene with trees, shrubbery and a gazebo adorned with Ionic columns-was convincing enough; and the cast's period costumes and powdered wigs were perfunctory but not unattractive. Led by Kristján Johnannsson, a well-known Icelandic tenor, the singers were excellent and the professional orchestra refined. By means of the slightly melancholy lyrical beauty of the musical passage, Mozart's aura emanated from the stage.

Before long, absurd touches emerged. In the midst of the non-stop singing and playing, a costumed footman would meander onstage periodically to offer the hungry and thirsty performers drinks and snacks to sustain them. One of the performers, playing a gardener holding a stuffed rabbit, seemed particularly woozy, now and again reclining on the stage. This turned out to be Kjartansson, the only non-professional singer in the cast.

Once in a while a musician would add drama to the proceedings by climbing out of the orchestra pit, quietly walking across the stage and disappearing for a spell, presumably to relieve him- or herself. The performance didn't miss a beat. Most funny and campy of all, the conductor, David Thor Jonsson, led the orchestra with exaggerated gestures, almost parodying his role. Wearing tails and sometimes wielding a baton, he flailed about at the edge of the orchestra pit in a way that seemed to invigorate if not inspire the strained cast and orchestra. Although he never really upstaged the opera, he acted more like a frantic ship captain during a storm than a Toscanini at the podium.

An hour in, the production was totally mesmerizing. Mozart's score transformed into a minimalist composition like an endless Philip Glass riff. I was lost in the subtle nuances of the singing and orchestration at each cycle. After a half-dozen or so repetitions of the aria, the orchestra would tune up, adding a spellbinding sequence of atonality to the mix. In the end, Kjartansson's wacky exercise in hypnosis did indeed provide some unforgettable moments of bliss.

Ragnar Kjartansson, Bliss, 2011. A Performa Commission Photo: Paula Court. Courtesy of Performa.