On a summer night, the city of Canterlot slept. Glittering stars covered the sky, winking in the warm pall of summer air that embraced the city like a blanket.
With few exceptions, the only ones that stirred in this comfortable summer somnolence were Princess Luna and her Night Guard. The Night Guard patrolled in every level of the castle; their dim lanterns flitted by the windows like so many fireflies. More surreptitiously, a few patrols sparsely covered the outlying grounds.
While the patrols were dutiful, even diligent, they were also, if you wanted to get right down to it, mere ponies. The Night Guard had finite attention spans. The Night Guard had no reason to suspect trouble. The Night Guard had not been vigilant enough, for within this idyllic silence, there was a lone mare who tonight found herself in opposition to the Night Guard.
Stepping out from Pony Joe's donut shop, Twilight Sparkle casually said her goodbyes to its proprietor. She wore a simple cloth pack securely attached by a strap, and her face had an unusually grim set to it. Turning, she walked away from the shop at a slow trot, and paused in an alley. A faintly ticking watch came out of her pack and floated in front of her with a dim glow. With no more than a few seconds of contemplation, Twilight replaced the watch and screwed up her courage. It was now or never. There was a wavering, brilliant glow, a small pop, and then Twilight was no longer in the alley.
Wincing at the conspicuous sound and light, Twilight found herself atop a balcony of one of the towers of Canterlot. Looking out over the city, she recognized one of the nearby towers. It was where she had become Celestia's apprentice, where she had earned her cutie mark. With a sinking feeling in her chest, she looked, lost, back at the castle proper.
Twilight felt as though she could have stayed in that trance until dawn, but it was broken by the insistently growing sound of approaching hoofbeats. Snapping back to attention, she searched in the stark light of the stars and moon for curtains that she knew should be there. With only seconds left, she dashed behind the dark velvet curtains, as unseen as she had hoped.
“Did you hear something?” said one voice.
“No. You've got to calm down, rookie. Not every bump in the night is a threat,” said another voice, horribly familiar to Twilight's ears.
“I mean, take a look at these curtains,” it continued, “they flap with the breeze so much that it's a wonder you're not hearing something now.”
“...fair enough, Captain. I'll continue on my beat,” replied the first voice, slightly peevish.
There was a brief pause, and then the sound of a single set of hoofbeats, walking away. For a moment or two, there was merely the soft sound of another pony breathing, facing the balcony. Then, the soft clack of hoof against stone as the pony turned around.
“You can come out now, or I can make you come out.”
Sheepishly, Twilight brushed aside the curtain with a flourish, and looked into the face of her older brother.
“Twilee? What... what are you doing here?” Shining Armor whispered urgently.
At first unable to meet his gaze, Twilight steeled herself and looked into his eyes. “I memorized the schedule for the Night Guard. This is one of the few vacant spots during the changing of the guard. I think that's because its pretty inaccessible, and then who would even be crazy enough or powerful enough to teleport directly outside the Princess's chamber? The-”
“No, that's not what I mean,” Shining Armor said in a desperate attempt to cut off her rambling before she hijacked his own train of thought. How did she even get a copy of the Night Guard's schedule? Had she stolen it from him?
“I know, and I'm sorry,” said Twilight sadly.
At this, Shining Armor looked back at Twilight. Her eyes were big, and her lip wavered in that peculiar way that had never failed to find purchase within his sympathy. “It's okay, I'm sure the Princess will forgive you, we'll just explain-”
“No, I'm sorry,” said Twilight, now interrupting him.
A terrible green glow surrounded Twilight's horn, and within a heartbeat, a green jet arced from her horn and lanced into her only brother, the Captain of the Guard, Shining Armor. He had time only to widen his eyes in a shocked expression before slumping to the floor with a grunt. Gingerly, he was picked up by Twilight's magic and tucked behind the curtain.
Twilight took a minute to stop and think:
The first patrol wouldn't return until another fifteen minutes. The Captain of the Guard was given free rein to oversee the entirety of the castle grounds and so-
*her throat caught*
-Shining Armor wouldn't be missed until he failed to report in at the end of his shift in midmorning, and he would awaken no later than noon even if he weren't found.
Satisfied, Twilight turned from the balcony to once again consider the castle itself. The curtains that separated her from the Princess seemed to rise up at her attention, forbidding her entry. With a snort, Twilight rolled her eyes and walked softly into Celestia's quarters.
The room was as it ever had been: clean, simply, though not plainly, outfitted, with a comfortable-looking queen-sized bed. The sides of the rooms were lined with bookshelves, and Philomena's cage was mercifully empty. In the middle of the bed, sleeping fitfully, was the immortal ruler of Equestria, Princess Celestia. Her uneasy rest was punctuated by grimaces that were unbecoming to such a regal face.
Twilight, framed by the silvery light of the night sky, approached Celestia, expression unreadable. She looked from one end of the bed to the other, and then sighed.
Forcing herself to turn away from the bed, unable to give aid or comfort, Twilight again pulled out her watch. Putting it more fully into the starlight, she read the time and frowned. With another fierce effort of concentration, Twilight began to teleport. She vanished with a pulsing, purple light. Celestia stirred for a moment, and then returned to her troubled dreams.
Twilight's destination was quite far from the castle proper, even for her. With a gasping huff, Twilight staggered to her feet outside the Castle Labyrinth. She hadn't much time! Wheezing, Twilight struggled through the outer hedge wall, parting the tall bushes with magic.
Twilight could hear the patrolling Night Guard just on the other side of the wall. Trying to calm her nerves, she focused on steadying her breath. Shakily, Twilight set out from the entrance towards the center of the maze. She had, of course, memorized the layout long ago, never imagining that she would be putting that knowledge to use. Not like this, anyway.
Running on automatic, Twilight found herself standing still after a few short minutes. Her breath caught, briefly, before returning in a rush of dry night air. Finally, she had reached her goal. She drew out of her pack one of the six most powerful artifacts of this world, known to some as the Element of Magic, and placed it atop her head. She then neatly took off her pack and lay it on the ground. Finally ready, she drew her gaze upwards and steeled herself.
Princess Luna, relieved at the tranquility of the night and its uneventful passing, moved to wake up her sister from what she feared had been another restless night. Groggily, Celestia awoke, stretched, and walked to her balcony. Looking into the city, she beat her powerful wings and began to rise into the sky with the first light of dawn. It was when this light began to pass over the sky that Twilight knew she had run out of time. Shaking partially from anxiety, partially from something else, her eyes began to glow with an inner light, and she began to free Discord from his stony prison.