Werckmeister Harmonies

The film can be seen as an allegory of post-World War II Eastern European political systems - told as a black-and-white cinematic poem with 39 long, single-camera takes. It examines the brutalization of a society, its political systems and ethics through the metaphor of a decaying circus whale and its star performer. It is set in a desolate, isolated small town in Hungary during Soviet times.
The film starts with JÃ¡nos Valuska, a simple person, conducting a poem and dance with drunken bar patrons. The dance is of the total eclipse of the sun, which disturbs, then silences the animals. It finishes with the grand return of the warm sunlight.
One of the significant reoccurring characters in this plot is the subtle transitions between light and darkness. The first appearance of this motif is a lamp in the bar, moving to a door into the darkness. The circus arrives like a Trojan Horse in the darkness of night. A window is opened as a glimmer of hope and dressed to shut out the world. The antagonist is only ever seen as a shadow.
JÃ¡nos' uncle GyÃ¶rgy is a composer, and therefore one of the intelligentsia. GyÃ¶rgy observes the imperfection and compromise of the musical scale (as defined by Andreas Werckmeister a historical theorist). GyÃ¶rgy proposes changes to the scale to make it more harmonious. This utopian approach to music represents a flawed, naive idealism that never can be achieved; it is not developed any further in the film or the book. It is just a statement indicating that human governance will always be flawed.
GyÃ¶rgy's estranged wife tries to leverage her political and social status by giving GyÃ¶rgy a list of names to recruit for the "clean up the town movement" (with the blessing of the police chief).
However, a stuffed smelly circus whale and its star performer, Prince, come to town in the silence and darkness of night. This is a metaphor for a bloated political system and the unseen Prince who represents the power of politically inspired, emotive dogma.
JÃ¡nos philosophizes about God and the beast.
The post office workers are unsettled by the ominous signs of the circus' arrival and are disturbed by the cloud that settles over each town it visits, a reference to the spread of the externally imposed centralised monolithic government system onto all the Soviet buffer nations just after the war.
GyÃ¶rgy's struggling cobbler brother gets the list and passes it on to the agitated throbbing masses in the town square who are unhappy at public services failing. GyÃ¶rgy's former wife sleeps with the drunk gun toting police chief.
The presence of the whale and the Prince stir up the masses. JÃ¡nos overhears the circus master losing control of his faceless Prince, who is becoming drunk with his own voice of revolutionary dogma. The circus master disowns him. The Prince, now free, inflames the masses, and the people riot.
The film is shot as a visual poem, and has been described as both beautiful and haunting. Lengthy single-shot scenes with a hypnotic and rhythmic pace build up to the peaceful observation of the thuggish destruction of the hospital and its patients. The rioters are brutal. Their inhumanity almost seems normal and natural. When the rioters finally come to beat a helpless old naked patient, they see their impotent, sad and powerless selves. The patients they are destroying in the hospital are themselves.
After the riot, JÃ¡nos comes across the diary of a rioter. It explains that the rioters did not know what they were angry with; so they were angry at everything. Then it recounts the mobs horrendous rape of two working class post office girls.
JÃ¡nos comes across his killed cobbler uncle who got naively involved in the riot. JÃ¡nos is told, by his cobbler uncle's wife, to leave town for his own safety.
He is intercepted by a helicopter. He finds himself committed to a mental institution with caged beds (a tool of the time for dealing with political dissidents). JÃ¡nos appears drugged and broken.
GyÃ¶rgy, his composer uncle, is evicted from their society house but gets to live in a shed in the garden whilst GyÃ¶rgy's former wife, with her new status as a collaborator, now occupies the big house with the police chief. The intelligentsia is displaced by political opportunism.
GyÃ¶rgy tells a vacant JÃ¡nos, in the ward, that if he is released from the mental institution they can live contentedly together in the shed with his piano. GyÃ¶rgy also mentions that he has re-tuned the piano so that is now like any other, a personal capitulation apparently abandoning any present hopes of reform. JÃ¡nos just stares.
It finishes with GyÃ¶rgy looking directly into the eye of the whale, then, walking away and looking back at the now sad and disheveled whale, destroyed by the rioters the night before, its rotting carcass slowly enveloped by the fog which gets whiter and brighter. Warm bright sunlight returns.

Question: What were the rioters angry at?
Answer: everything