What was I guilty of? Why had I been arrested?
The treatment of political prisoners during the Chinese Cultural Revolution was brutal, as is the case in many one-party states. The Communist state, led by Mao, whose picture was everywhere and on whose authority the cultural revolution was carried out, used constant propaganda to make sure that the state was viewed as all powerful and all important. When someone is denounced as a counter-revolutionary or enemy of the state, few question it, even if there is little evidence. Rumors or seemingly innocuous statements are enough. Since the state is even more important than friends and family, it cannot be questioned. Ma Bo, whose is denounced and arrested, finds that he doesn't even known the charges against him, and when he asks, it only confirms his guilt.
Prisoners are interrogated and systematically broken down. They are constantly told they are guilty, that they are enemies, and told to confess. They are utterly isolated, as Bo finds himself; his childhood friend denounces him, and his own mother believes he's guilty and won't talk to him. Physically, he is beaten and confined to a cell, where for a time he is shackled. Food is denied, conditions are brutal, and it's cold. The only way to get it to stop is to confess, and he eventually does write a confession, even though he doesn't believe he's guilty. The confession results in him being exiled and sentenced to hard labor.