Twilight Sparkle was at home one morning when she got the distress letter from Princess Celestia explaining that she had been keeping something secret from everypony, especially Luna, about a line from the well known story "The Mare In The Moon." The line was "The stars will aid in her escape." Just who were the stars, what significance could they possibly have, and what was Princess Celestia's secret? All of these questions can be answered through the pages of Luna's diary that has been hidden for 1000 years. Twilight gains possession of the diary and goes through a sci-fi adventure watching Luna's past, learning more about Luna's transition from Princess to Nightmare Moon, and the problems that caused it to happen.