After her first foray into making friends with Trixie, Starlight Glimmer has been more open to the idea of making new friends. Not all meetings work out as expected, but for the most part, things have been going smoothly for her. But within the castle's library, she meets a visitor named Sunset Shimmer, the mare's presence surprising her. And even though Starlight finds Sunset to be unlike anypony she's ever met before, there are some things she'd rather keep secret. As it turns out, Sunset has some secrets of her own.