What is the author's tone in In the Belly of the Beast: Letters from Prison by Jack Henry Abbott?

The overriding tone of In the Belly of the Beast could be said to be anger. Abbott is irate at his own present circumstances of an indefinite prison sentence. He believes his placement in prison is the result of a gross injustice and that he did nothing to earn his lifetime of incarceration and punishment. Extremely indignant, Abbott demands an apology from the prison system for the wrongs they have committed.