This concert film stages a never-realized gala at Budapest’s Opera House, stringing together eleven diverse numbers - from operetta and folk dance to popular songs - introduced by Vera Sennyei’s tongue-in-cheek on-stage announcements. Though framed as a live opening night, most performances were in fact shot in television studios, creating a playful pastiche of televised spectacle rather than a traditional concert film.

The title character in Maria Nover (Sister Maria) is played by Eva Szorenyi. A convent-bred lass on the verge of taking her final vows, Maria falls in love with a handsome artist, portrayed by popular operatic baritone Sandor Sved. Due to a silly misunderstanding, she walks out on Sved and marries his best friend Paul Javor. The frustrated suitor quits the art world to become a world-famous concert singer. Years later, he returns to reclaim Maria, only to find that she's not only still a wife, but also a mother and a dedicated nurse. Gracefully bowing out of her life, the Pagliacci-like Sved continues his singing career to assuage his broken heart.