Scene 1
Saliery, who has achieved fame and recognition by his hard work, is deep in thought. He is torn by torturing envy of Mozart:
"O heaven, where,
Where is the justice, when the holy gift,
Immortal genius, comes not as reward
For any burning love or self-denial,
Labour, diligence or prayer, but lights
It radiance instead in heads of folly
And frivolity?"

Mozart appears. With him is an old, blind man with a violin, who played Voi che sapete in a tavern. To entertain Saliery, Mozart asks the old man to play "a little Mozart ". He plays an aria from Don Giovanni. Infuriated, Saliery drives the old man away:
"When Raphael's madonnas are defiled
By worthless daubers, I do not find it funny".

Mozart sits down at the piano and plays Saliery his new "trifle". Saliery is stunned:
"What profundity!
What boldness and what perfect form! Mozart,
You are a god, and do not even know it".

Saliery offers Mozart to have dinner together. Having accepted his friend's invitation, Mozart leaves. Saliery makes up his mind to poison Mozart:
"I have been chosen: I must be the one
To stop him. Otherwise we all will perish,
All of us priests and ministers of music
Not only I with my dull-ringing fame".

Scene 2
In the Golden Lion Tavern Mozart and Saliery are having dinner and talking. Mozart is gloomy and thoughtful. He tells about an odd stranger in black, who recently visited and ordered requiem - a requiem mass. Mozart confesses:
"He gives me no rest night or day,
My man in black. He's everywhere behind
Me like a shadow".

Saliery tries to distract Mozart from bad premonitions. Discretely, he tosses poison in Mozart's glass. Deep in thought Mozart drinks his wine and performs a piece of the requiem. Saliery cries. Mozart feels bad and leaves.

And once again painful doubt comes to Saliery's soul: is it really true, that, as Mozart mentioned in passing, "Genius and villainy are two things incompatible".