AMADEUS, Porchlight Music Theatre Chicago, at Theatre Building Chicago. The narrator of Peter Shaffer’s insistent biodrama–court composer Antonio Salieri–incessantly attacks God for deserting him, a pious puritan, while bestowing genius on his Viennese rival, Wolfgang Amadeus Mozart. Shaffer sets up a historically dubious contrast between the devout Salieri, with his “desperate sense of right,” and the “obscene child,” who alternates scatological baby talk with tactless boasting. Pleading for absolution but fully relishing his evil deeds, Salieri tells how he ruined Mozart at court and hints that he poisoned the world’s greatest composer.

L. Walter Stearns bases his revival on Shaffer’s seventh revision of the 20-year-old work, which somewhat softens the melodramatic final events. Brendon DeMay brought irresistible charm and touching vulnerability to the trusting Mozart in the final preview I saw, but Bil Ingraham as Salieri lacked the gravitas to balance his rival’s frivolity, conveying more snit than suffering.

The supporting work, especially Kingsley Day’s dithering Austrian emperor, is sterling. Robbie Hayes’s setting–broken arches and shards of stained glass–cleverly conveys Salieri’s crisis of faith. And musical director Eugene Dizon delivers an engaging live backdrop of mostly Mozart (though it sometimes threatens to drown out Salieri).