What is the main conflict in A Dangerous Fortune by Ken Follett?

The story begins with a bunch of schoolboys disobeying the rules and going for a swim at the quarry pool. While they are teasing and bullying each other, one of them, Peter Middleton, drowns. The official story told at the inquest differs from the true events, and the cover-up and treachery begin that is to continue for three decades as their schooldays follows the characters through their lives.