There were one thousand five hundred forty two registered citizens living in Ponyville. At the moment, Twilight Sparkle could account for exactly one of them.

When she woke up this morning (behind schedule!) there was no Spike to greet her with a cup of coffee and the day’s itinerary. He was nowhere to be found in the crystal palace. Odd, but not unheard of. She thought perhaps she recalled some special event today that might have called him away, but her sleep-addled brain, deprived of caffeine and proper scheduling refused to fill in the blank. And after all, Spike was prone to flitting off to assist Rarity with no notice. So Twilight, while miffed, was not alarmed.

She did become alarmed, though, when she made her way into town to find it deserted. Her normal route into town brought her first past the schoolhouse, where no fillies and colts played. When she entered the town proper, no ponies milled about the market, searching for deals from unstaffed stalls.

At first, it was a mildly alarming curiosity. Twilight peeked into houses and shop windows, assuming ponies to be hiding from her in some large, organized prank. She knew if she looked hard enough, she’d find somepony and the game would be up. Rainbow Dash would pop out and bray in laughter, Twilight would concede a job well done, and then everypony would laugh together.

Except she couldn’t find a single pony anywhere in town. As Twilight made her way into the town square, it seemed as if everypony had just… disappeared. Shelves were partially stocked. At Sugarcube corner, fresh-baked bread sat on the cooling racks, still hot. Important papers sat scattered around the mayor’s desk willy nilly, half sorted. (Until Twilight organized them.)

What started off as a game of hide and seek, became a desperate search for somepony, anypony left in the town. Twilight dashed street to street, calling out in desperation. She received no replies. She took to the sky for an aerial view, but she could see no movement. She wanted to contact Princess Celestia, but of course, no Spike. She tried a sending spell of her own, but received no response.

Had some disaster befallen the town? There was no sign of physical damage. Not even of a struggle. Why was everypony just… gone?

Carousel Boutique: empty. Sweet Apple Acres: abandoned. Fluttershy’s cottage: not even a solitary squirrel. Panic set it. Twilight began to imagine things. Hear things.

“Fifteen forty… Fifteen forty...” It was distant, on the wind. Wait, that wasn’t an auditory hallucination.

“Fifteen forty. Fifteen forty.” Twilight followed the sound. It was coming from the direction of the palace.
“Fifteen forty! Fifteen forty!” When her crystal castle came into view, finally, a beautiful sight. Another pony. There, bouncing back and forth in front of the door, chanting to herself, “Fifteen forty! Fifteen forty!”

Twilight landed in front of her. “Pinkie! I’m so glad to see you! What’s happened!? Where is everypony!?”

Pinkie grinned at her. “‘Bout time! Go inside, silly!”

Twilight, simply relieved at finally having some contact with another pony, obeyed.

“Fifteen forty one!” Pinkie chirped, and followed her friend inside. “Aaaand fifteen forty two! Everypony’s in!” she cheered as she bounced beneath a banner that read, “Suprise! Happy Birthday, Twilight!”