This story is a sequel to Corruption of Dawn

It has been three months since the catastrophic attack on Canterlot by Sombra's army. Twilight has yet to truly recover from the event that she blames herself for. But the forces of Darkness are striking again in search of the Etna Key to free the dreaded Red-Black Beast. With time now short, Twilight and her friends must find the Etna Key before it's too late.

Darkness is a living thing. It consumes the strong and destroys the weak, not knowing the meaning of mercy. It corrupts and devours until there is no light left within one's heart.

What happens when the young mare who wields the Element of Magic succumbs to the Darkness?