Night Shade, a brony with a side hobby of Alchemy creates a portal that can travel between dimensions. But with this portal, a big responsibility comes. Slendermane, the guardian of the portal, tells Night Shade, along with with two of his friends and an almost complete stranger, that that they're in charge of defending the most important universes of all. They're separated from each other, each given a device that allows them to keep in contact with Slendermane, each other and the outside world. The story mostly follows Night Shade on his quest to defend Equestria from various groups who want to enslave Equestria and remove all beings that do not belong. Night Shade tags along with Vinyl Scratch and Octavia, along with many other ponies, who turn out to be more than meets the eye in this massive thriller.