Trevayne by Robert Ludlum

Trevayne was a self-made millionaire by the time he was thirty. Then he went into government, carving our a brilliant, honourable career. Now he was head of the biggest foundations in the USA. He was fearless, intelligent and incorruptible. No one could touch him - or so he thought. Then his investigation into the 'secret government' led him beyond the corridors of official power into a nightmare maze where Mafia leaders and 'legitimate' billionaires mixed, where Congressional seats and even the Presidency itself were bought and sold. And where a man like Trevayne could be a dreaded enemy, a duped victim or a king.