This story is a sequel to Inside Pinkie Pie's Mind - Pinkie's Secret

While she's having an amazing time with her friends at a party she planned, Pinkie decides to come clean about who she truly is and introduced Pinkamena. But before she could do just that, something's happening within her mind. A dark force is in the works.

And their target; Pinkamena!

This story maybe a sequel, but it can be read as its own story as well.