Castrati were the undisputed superstars of 18th-century musical culture, driving crowds wild with their intoxicatingly androgynous virtuoso voices. Nicholas Clapton, countertenor and castrato historian, analyses the anatomical mysteries of the castrato and the biological implications of castrato. He travels to Bologna, the adopted home of Farinelli, perhaps the most famous castrato. And for the first time in Britain, American male soprano Michael Maniaci, a young Baroque opera singer whose voice did not break at puberty, performs Mozart's Exultate Jubilate, a piece originally written for castrato Rauzzini.