When a ghost haunts Canterlot High, the girls wonder how to deal with such an entity. Desperate, they seek the help of the Princess friend who knows friends who can help them. But with the Real Ghostbusters retired, the Princess will have to send in the next best thing. The Extreme Ghostbusters.

Four months have passed since the Ghostbusters mission in Equestria. Now they must return to protect it from the ghost of Nightmare Moon who still desires to make nighttime eternal in the land. Will the boys and and ponies defeat this ghostly monster, or will all of Equestria fall into eternal darkness?

The Ghostbusters have taken on a hundred foot Marshmallow Man, the Boogeyman, and Cthulhu. But are they prepared to take on the dark ghost of an evil king that once terrorized a kingdom located in a land of magical talking ponies? MLPxReal Ghostbusters crossover.