A mysterious messenger, a pouch of gold, and a commission for a mass for the dead: the story behind Mozart’s Requiem in D minor sounds like Gothic fiction, and much of it was deliberately manufactured. This episode separates the documents from the myth. The anonymous patron was Count Franz von Walsegg, a wealthy amateur who habitually commissioned works and passed them off as his own, and who wanted a requiem to memorialize his 20-year-old wife Anna. Mozart took half the fee, fully orchestrated only the Introitus, sketched the vocal lines and bass for the Kyrie, Sequence, and Offertorium, and broke off after eight measures of the Lacrimosa before dying on December 5, 1791.

We follow his widow Constanze’s scramble to finish the score and collect the second payment: Joseph Eybler’s abandoned attempt, Franz Xaver Süssmayr’s completion of the Lacrimosa and the Sanctus, Benedictus, and Agnus Dei, the recycled opening movements pasted on as an ending, and the forged signature dated 1792. We examine what is demonstrably Mozart’s, from the basset horns and trombones to the Handel-inspired double fugue, the 1960s discovery of a sketched Amen fugue, the poisoning rumor that fed the Salieri legend and the film Amadeus, and the corner of the manuscript torn off at the 1958 Brussels World’s Fair.

• Why Mozart wrote the vocal lines and bass first, like load-bearing walls in a blueprint
• How a widow with no royalties and no copyright turned an unfinished manuscript into her family’s survival
• Süssmayr’s shortcuts, including the two-chord ending scholars say Mozart never intended
• The debate between honoring the historical Süssmayr version and modern restorations using the Amen fugue
• The still-missing scrap bearing what may be the last words Mozart ever wrote