Twilight thought she knew everything there is to know about Equestria, from its inhabitants to its various locations. But one day, while she was helping Fluttershy out in the old castle in the Everfree forest, she discovers a secret passage that leads to an entirely different version of that same castle. Bigger, different but still eerily familiar, it's almost a whole new world to explore for the unicorn.
Driven by curiosity, she explore this alternate reality, completely oblivious to the danger she's putting herself and all her friends in.
The King always keeps a close eye on his visitors... even outside of his domain.
This story is set in the same continuity as Fear The Hypnotist, though both stories should be able to stand on their own.