Twilight teleported herself and Spike off of the speeding train car that they were riding. Princess Celestia's response to her inquiry about the Glow instructed Twilight to get off at the base of the mountain. Celestia's letter to Twilight had been … odd. Normally, the unicorn's teacher was forthcoming with information. However, Celestia's response had been terse, simply instructing Twilight to meet her at a clearing at the bottom of the mountain the next morning. Furthermore, the Princess had instructed Twilight to tell nopony of her trip to Canterlot Mountain. Spike was not a pony, so Twilight allowed him to tag along on the journey.
There were no stops on the Ponyville-Canterlot line at the promontory’s base, so teleporting was Twilight’s best idea for a quick exit. When the cast the spell to get off of the locomotive, Twilight failed to consider her own and Spike’s momentum. Thus, when the two reappeared, they found themselves hurtling toward the mountain's sheer rock face. Thinking quickly, Twilight conjured one of Rarity’s fainting divans, using the sofa to catch herself and her speeding companion.
“Ah, Twilight, you’re right on time. I see you’ve brought Spike despite my request, but I believe that he can be trusted with the knowledge that I am about to share,” Celestia announced, stepping out from behind a tree at the edge of the clearing. Twilight was surprised: she did not know what could be causing Celestia to act so secretively. Spike was also surprised: he did not know how that tree could hide Celestia’s massive form. Wisely, the young dragon chose to keep this observation to himself.
“Princess, what’s this about? Why are you speaking so cryptically?” Twilight asked.
“You’ll see in a few minutes, my faithful student,” Celestia replied. “Come, follow me, you two.” The Princess turned toward the blank face of the mountain and walk towards it. Twilight could see a small hole a few feet off of the ground. Celestia bent her head down and inserted her horn slowly into the gap, casting a spell Spike recalled what Twilight had told him during “the Talk,” especially the part about holes, pointed objects, and the need for lubrication in tight spaces. Again, astutely, he chose to keep this thought to himself.
Celestia removed her horn, and there was a rumbling sound. A massive rectangular entranceway lowered from the rock, showing the three a hallway (lit with enchanted lanterns hanging from the ceiling) that gradually descended deeper into the earth. Celestia began walking down the corridor, and, after briefly glancing at one another, Twilight and Spike followed her.
The group had been walking for 15 minutes when they came upon an ornate red door, decorated with gold swirls.
Celestia turned and looked at her guests. She said in a serious voice, “Twilight, Spike, what you see in this room must remain among us. Only Luna, Cadance, and I know what is inside. Promise me that you will keep this a secret.”
“We promise, Princess,” replied Twilight.
“Thank you, both of you. Now prepare yourselves, as I do not know how mortals will react in the presence of the Glow,” Celestia announced. She opened the door, and they all walked into the Glow’s chamber.
It took a moment for Twilight and Spike’s eyes to adjust to the relative dimness of the room. Upon a plinth in the sanctum’s center was a glowing gold artifact. It looked like a radioactive ice cream cone, with a ridge circling around its vertical length.
“Holy shit,” exclaimed Spike.
“Spike!” Twilight admonished. “Watch your language in front of the princess!”
He responded, “No, Twi, I mean it looks like a glowing turd!”