Mozart & Salieri is an opera in one act by Nikolai Rimsky-Korsakov set to a Russian libretto taken almost verbatim from a novella of the same name by Alexandr Pushkin.
It's based on the oft-disputed legend that Salieri poisoned Mozart out of jealousy for his genius.
The novel occurs in a single afternoon and evening with Mozart dropping by Salieri's apartment in Vienna to play his nearly-completed "Requiem."
The two go together to an inn for dinner where Salieri poisons Mozart.