Writing Prompt: Keeping a Secret

Have you ever seen the old British spy series - The Prisoner?  It starred Patrick McGoohan as a British spy who tried to retire.  

Patrick McGoohan (Public Domain)

His agency abducted him and retired him to a strange seaside community where he was continually questioned about why he resigned.  The interrogators want information and by hook or by crook they were determined to get it.  The Prisoner was an awesome show that operated on many levels.  It's also a bit of inspiration for a writing exercise.  Today's writing prompt is to write a short piece of fiction about -

a person who knows something but doesn't want to share that knowledge.