4 ideas
Paul Pennyfeather, a blameless theology student, is debagged by the drunken Bollinger Club at Scone College and then sent down for 'indecent behaviour' while the rich culprits are only fined. Later he is engaged to the society hostess Margot Beste-Chetwynde, is arrested for running her South American brothel business in her place, and serves her prison sentence, while she marries the Home Secretary and arranges his fake death and escape.
The college authorities fine the wealthy Bollinger members, whose fines pay for the college port, and expel the poor student they assaulted, because the rich bring in money and the poor student does not. The novel repeats this pattern in the prison and in high society: guilt falls on whoever has the least standing to refuse it, not on whoever acted.
Otto Silenus says life is like a big wheel at a fairground: some people (dynamic) scramble on and are thrown around, some enjoy it, and others (static) sit in the middle or watch from the stands and are never touched. Paul is a static character who was pushed onto the wheel by accident. His passivity explains why he survives disasters without learning from them or being changed by them.
Waugh reports atrocities in the same flat, unsurprised tone as trivial social events: the boy Lord Tangent is shot in the foot at sports day and later dies of it, and a prisoner saws off the chaplain's head. The narrator never shows outrage, so the reader has to supply the moral judgment. That makes society's indifference the thing being accused.