Hooflantis is an ancient city of legend that holds a powerful talisman. This talisman is known to be more powerful than the Crystal Heart! It sank under the sea a thousand years ago at the conclusion of the Pony Sisters war against Discord. Now it's back. This sudden event has raised many questions. How did it rise back out of the sea? Why does it look as clean as the day it sank? Who's the pony known only as Ember? And what is this mysterious talisman said to hold untold power? Join the mane six in a race against time to find the talisman before the darkness that lurks inside the city does.