The grand opera house echoes with their illicit tryst, their voices intertwining in a symphony of desire as they give in to their taboo lust. The sister, a soprano, sings out in ecstasy as her brother, a tenor, brings her to the brink of orgasm with his expert fingers. Their bodies press together, their hearts pounding in time with the music. The brother's voice deepens as he enters his sister, their bodies moving in perfect harmony, their voices rising in a final, passionate crescendo that leaves them breathless and spent, their secret love story etched in the very walls of the opera house.