"Glorious!" is based on the life of Florence Foster Jenkins, the legendary New York heiress and socialite who wanted to be a great operatic diva despite having one of the worst signing voices in history, and who used all her money, charm and unstoppable willpower to make it happen. The soprano voice she hears in her head is beautiful and it never occurs to her that this is not the sound issuing from her mouth. The play opens in 1940s New York in the apartment Madame Jenkins shares with the English actor St Clair, and finds her auditioning her pianist Cosme McMoon. Add in a Mexican maid who speaks no English (while Madame Jenkins knows no Spanish) and her ditzy companion Dorothy and follow their exploits until the crowning moment of a sell-out concert in Carnegie Hall.