These first chapters re-introduce us to both Princess Twilight Sparkle's ponies and Sunset Shimmer's equestrian girls a few years down from the events of the Legend Of Camp Everfree.
People change and friendships grow stronger or are forgotten as adulthood approaches. But that's only part of the girls and ponies problems as an ancient evil as old as time threatens both universes, lucky for them they have the help of someone that was there since the beginning and has first hand experience with it all.