It was a beautiful summer night in Equestria. Everypony was in bed and sleeping the night away. That is, except for one silly filly who decided to run off into the woods to play. As it got darker and darker, the filly saw another pony off in the distance. As he stared at the pony, he began to feel faint and heard a static noise. Figuring it was just his camera, he just shrugged it off and went closer and closer. The pony turned around to reveal no face. The next morning, the news network put a story about the filly, who has gone missing. Everypony thought he was just lost and would come home the next night. He didn't. Then, two more disappearances were reported on the news. Twilight decided to do some research and found a very old myth called the Slender Horse. A frightening creature that has no face, extremely long limbs, and tentacles coming out of his back. Twilight warned the entire kingdom about it. They all barricaded their doors. Praying that the night will pass and they can escape to another country. But will they survive? If you guys don't understand the lab reports, I will explain. After the Slender Horse case, Twilight and her friends have gone insane from Slender sickness. They are in a mental repair institution. The lab reports are the doctor's progress on the process of restoring the Mane 6's sanity, as well as their progress to finding out what happened though their eyes.

Edit: To clarify, Subject 46523 is Twilight, Subject 165 is Rainbow Dash, and Rarity is Subject 3614. I will update for the others if I include them.