Dusk lives in an era of political turmoil, as the feuding between the three pony tribes has escalated to its near max. His life is no exception for turmoil; he has to make do with what he has every time it changes.

This is a sidestory of Dawn, which you can read here. It's not a direct sequel or prequel, much of it happens before they meet each other. They really only start to cross in later chapters.