Humans were thought to be a myth in Equestria, but Twilight knows that they do exist, if not in her own world, then in the one on the other side of that mirror--and perhaps others.

In the aftermath of Tirek's assault and the establishment of her own Kingdom, the opening of the chest brings to threatens to bring to light a shadow that has unknowingly cast its pall over the land for for many centuries. As Twilight's dreams are plagued by music and death, might the chest have been was better left unopened?

Where did the Tree of Harmony come from?
How was the Crystal Mirror made?
Is there a connection between the many threats that have plagued the land?
Who is the imprisoned maiden whom sings among fire and blood?

All of Equestria may find that Pandora's Box was better left unopened.

Crossover with the Ar Tonelico video game series.