Glass Horizon

"Sam peered over the edge of the building, the only edge for countless miles. He wondered if anyone watched him in that moment, standing up there on the roof, and questioned how he had got out there or what he was doing. He wondered if they watched him now in the same way Sam had watched that man outside the glass all those months ago, that strange man with his fear and his pistol."

The year is 2234 in a world without borders and without war.
In an enclosed glass world where equality and peace had been long since achieved, trouble stirred in the heart of a young man who wanted nothing more than to feel at one with his autonomous environment. If this world was so perfect, why did Samuel Ward want to leave?
What was the man on the other side of the glass so afraid of? What was Sam so afraid of?