Looking for a fantasy about a patriot betraying their country.

I'd love to read a book that follows a person who fully trusts their government and its leaders and joins it out of patriotism but grows disillusioned over time and eventually betrays them after discovering what lies beneath the vail.

The character doesn't have to be a soldier necessarily, it could be a more academic role like an investigator or clerk privy to classified information and systems. Maybe something resembling Edward Snowden's story.