Amadeus is Antonio Salieris tragic story, a capable but not ingenious composer, which appears before us at the beginning as gentle, kind and very religious person, but in the end meets a furious fight with the Lord. This story lifts a set of questions of the relations with the Lord, about the nature of the genius and jealousy. The key subject of the film is that why the Lord gives people a desire to reach something (in this case to become a brilliant composer), but doesn't give any equivalent abilities.
The movie begins in a madhouse where already old Salieri got after a suicide attempt. The young priest comes to profess him, and Salieri tells him the story of his life, and the events of the movie transfer us to Vienna thirty years earlier
Salieri's story (F. Murray Abraham) originates in those days when he was a court composer at the court of Roman Emperor Joseph II (Jeffrey Jones). He is successful and popular, pleased with his life and music. He is grateful to God to whom he swore eternal fidelity, for the granted success and glory. He hasn't yet met Mozart (Tom Hulce), but has heard about him and his music. Salieri is intrigued with his popularity and looks for a meeting with him. But when he at last notices Mozart, it becomes a shock for him, after all he sees him creeping on cards and untidily flirting with Constanze (Elizabeth Berridge) who later becomes his wife. Salieri is shocked, he doesn't understand, how so fine music can be written by this young fool.
Over time, after a number of painful humiliations Salieri realizes that all his works are insignificant in comparison to Mozart's music. He can't understand, for what the God betrayed him. Why he allocated blasphemous Mozart with so great talent, instead of him, Salieri? Antonio Salieri, who in all his life was a devoted Catholic, cannot believe that the Supreme chose Mozart, instead of him for so great gift. But most of all Salieri can't understand, why the Lord, having a kind feeling to his aspiration to music before, then broke it so cruelly. Once he exclaims in despair: All that I ever wanted was simply to sing to the Lord. He gave me desire of it which lives, as if the thirst in my body, but refused me in talent. Why! .
It starts to seem the unfortunate that the God specially creates the wonderful music through Mozart to show Salieri's mediocrity. It is heart-broken. He gave all his love and music to the God, even gave for the sake of him a vow of chastity. And now the Supreme laughs at his mediocrity. The enraged and lost Salieri renounces the God. In a tremendous scene he breaks a crucifixion from a wall and burns it on fire. He swears that henceforth he, Salieri, is the enemy of the God, and promises to revenge him by destroying Mozart.
All the rest of the film Salieri pretends to be the ally and friend of Mozart, at the same time making all efforts to destroy his reputation and to deprive his composition of success. Mozart is ill-advised, both socially and financially. His initial success at court soon disappears, and the numerous parties strike a crushing blow on his condition. Health, marriage and Mozart's reputation at court seriously suffer, but his music is still excellent. Too proud to teach, he just composes by his own, but it doesn't suffice to pay his wastefulness.
Then Salieri also thinks out the plan of his revenge. He makes Mozart believe that his dead father revived from his grave to order the Requiem (during the lifetime Mozart's father was imperious and cruel, he suppressed Mozart's creative aspirations), the belief, that the ghost of the father visits him, provoked at Mozart a nervous breakdown, and his thirst to alcohol became constant. Salieri's plan was mad and at the same time ingenious. It consisted in catching the finished requiem secretly, in killing Mozart, and then playing the requiem at his funeral, arguing that Salieri himself wrote it. He believed that stealing Mozart's fine requiem, he will steal it from the God himself. And if the story reminds him, Salieri, as an ingenious composer, thanks to the music stolen from the Lord, his revenge will be executed.
Meanwhile Mozart's friend Emanuel Schikaneder (Simon Callow) suggests him to write the opera a requiem mass. Mozart agrees and creates The Magic Flute. The opera makes a big success, but during the representation Mozart (who worked too much to finish both the requiem and the opera) faints from exhaustion and Salieri takes him home.
As soon as Salieri brings the seriously ill Mozart home, he provokes him to continue to write the requiem. Mozart says that he is too weak, on what Salieri in fantastically touching scene suggests to write down the notes himself from the dictation of Mozart confined to bed. Probably, Salieri hopes that he will be able now to reveal the secret of musical genius Mozart. Helping Mozart, he, probably, will understand and open a genius in himself. Mozart starts to describe the excerpt, and the music absorbs him, carries away with itself, buzzing and singing, gradually creating harmony. Salieri desperately tries to keep up with him, but at the end as Mozart puts a layer behind a layer more and more subjects in his music, his musical intuition leaves Salieri far beyond the limits. Salieri is confused, he simply doesn't understand what kind of music it should be. Mozart's genius stops and explains to mediocre Salieri everything that he understood the structure. Here we see the most decisive distinction between these two composers. Salieri never can reach greatness. After some time, Mozart, who everyday becomes weaker and weaker, stops to thank Salieri, that he always was his friend, adding thus that he has precipitately thought that Salieri never loved his music, and now he understands, how mistaken he was. It touches Salieri to depth of soul, despite all his rage, and he sincerely says: I confess. You are the greatest composer from all I have ever known.
The next morning Mozart's wife comes back home. Finding there Salieri, she demands, that he immediately left them and locks the incomplete requiem away, refusing to give it to Salieri. Constanze goes to Mozart's bed to console her husband, but finds him dead. Salieri's plan fails; he didn't manage to steal the requiem.
Mozart's funeral passes imperceptibly. He is buried in an anonymous mass grave.
The narration transfers us again to the madhouse, and we see, how much the young priest is amazed from Salieri's story. Aged Antonio tells the priest, that not he, Salieri, but the God killed Mozart. He says that the "merciful" Lord preferred to kill Mozart, rather than to allow Salieri to steal his music.
Then Salieri bitterly jokes that he is the patron of all mediocrities and will pray for the mediocre young priest and for all mediocrities in the world. The person on duty enters Salieris room, and takes him to a wheelchair to lavatories. As the way goes through the all madhouse, Salieri has to pass by a great number of mentally ill people, in wheelchairs, tied, talking profusely or simply looking around, with obvious signs of an idiocy. They symbolize the fight of imperfect people against the carefree Lord. Salieri welcomes them as if the Pope, telling them: The worldwide mediocrities, I forgive you, I forgive you, I forgive you, I forgive all of you...
The movie comes to an end, a close up on Salieri hardly closing tired eyes for he is haunted by memory of Mozart's irritating childish laughter which fills the final seconds of the movie.