The main actor spends very little time explaining himself. His sidekick, the young student, is struggling harder to put into words what one human being owes to another. In one episode they face two tasks, one even more horrifying than the other. After quarreling for a bit over who should do which, the young man suggests a coin toss, which the teacher loses. The young man takes care of his own horrible job, only to find the older man procrastinating about his, which provokes the outraged outburst that "coin toss is sacred, man." When you expose yourself in good faith to the outcome of a tool of chance, you live with the result. You hang onto that moral precept even though you seem to have left the world of virtue far behind, and the coin toss is about profound crimes that are disintegrating your identity.
In some part of us, we know there have to be moral laws even if we ostensibly think the universe is a vast, materialist, meaningless void.