The mines below Canterlot were collapsing. Twilight Sparkle and her group tried to find an escape. Debris fell from above.
Rarity used her gem-finding spell to search for an exit and led the group there. Rainbow Dash and Princess Cadence flew around in search of a pathway, with the unconscious Minuette on Cadence’s back. Lyra, Bon-Bon, Twilight, and Applejack tried to remove obstacles while Pinkie Pie warned the group of incoming boulders. Fluttershy looked out for anypony that might need saving.
Pinkie’s tail twitched as a boulder fell from the ceiling. Applejack kicked the boulder away.
Twilight lifted several rocks that were blocking the path.
The group was almost there. There was a light in the distance. But the debris fell down in front of them and blocked the path.
Everyone moved the rocks as they tried to escape. They had mere moments to escape.
The last of the obstacles were cleared. The group escaped the cave-in.
As they galloped out of the mines, they could see the entrance to the mines collapse. They panted as they made sure everyone was there.
“Everypony alright?” Twilight said.
“We’re fine,” Applejack said.
Just then, Minuette woke up. “What happened?”
The other ponies were shocked.
“Why does my head hurt?” Minuette said.
They saw that her eyes were no longer green.
Lyra approached Minuette and said, “You need to rest. You had a bad dream.”
Minuette left to find something for her head.
The group looked to the castle.
“Come on!” Twilight said. They went to the castle.
The wedding had started. Princess Cadence trotted down the aisle in her white and gold wedding dress. A large crowd gathered to see the wedding, among them was Silver Spoon.
Princess Celestia, Spike, and Shining Armor were at the other side of the aisle. The spell Cadence had over Celestia faded long ago. She wondered why she threatened to send Twilight to the moon, but more pressingly--
“Where are the bridesmaids?” Celestia said.
Cadence looked behind and saw that her bridesmaids were still gone. The crowd was shocked. They wondered where the bridesmaids are.
Everypony looked out the windows as they saw some of the mountainside crumble. Cadence took a closer look.
She saw her bridesmaids, one of her ex-bridesmaids and her friend, Twilight Sparkle, and another Princess Cadence. The sight shocked her.
Cadence answered Celestia. “They went to find something.”
“Did they find it?” Shining Armor said.
“Oh yeah,” Cadence said. “But I don’t think they’ll make it back to the wedding. Can we lock the doors?”
“Sure,” Celestia replied. “But why?”
“I just don’t feel safe with them unlocked like that,” Cadence said.
“I can assure you that the royal guard is watching over the wedding, and Shining Armor’s barrier is still in place. But if you insist.”
Celestia used her magic. The doors to the hall were locked.
“Thank you,” Cadence smirked. The wedding resumed.
In the skies above, Diamond Dust and her adviser were looking at the barrier. Apple Bloom picked up her sword with her mouth, Sweetie Belle levitated her scales, and Scootaloo grabbed the scythe with her teeth.
“Are you ready?” the adviser said.
“Ready,” Apple Bloom mumbled. She was having a little trouble wielding the sword.
“Ready,” Sweetie Belle said.
“Ready,” Scootaloo said.
“Good,” the adviser said.
Diamond Dust looked at the cracks at the bottom of the barrier. She saw that the changelings were also preparing to begin their invasion.
Twilight’s group had made it into the castle. They saw that the room was empty.
‘Everypony must be at the wedding,’ Twilight thought. They traversed to the grand hall, where the wedding was being held.
A few minutes later, they were at the doors. Twilight tried to open them.
“They're locked!” Twilight said.
Applejack and Rainbow Dash tried slamming the doors but they wouldn’t budge.
“What do we do?” Pinkie said.
“Um--” Futtershy said.
“Don’t say it,” Rainbow Dash said.
“There has to be something we can do,” Bon-Bon said.
Twilight was at the other side of the hallway. She began charging her magic.
The wedding continued. Cadence was already at the altar with her husband to be.
“...If there any objections or reasons why these two should not be wed,” Celestia said, “speak now or forever hold your peace.”
A purple light engulfed the doors at the other side. The doors were blasted to the middle of the aisle.
Twilight Sparkle had entered the aisle. “I have an objection!”
Cadence’s mouth was agape. “What?!”
“You’re not the real Cadence!” Twilight pointed her hoof at the bride. Rainbow Dash, Pinkie Pie, Rarity, Fluttershy, Applejack, Lyra, and Bon-Bon entered the room.
Cadence cried again. “Why do you have to try to ruin my wedding?”
“Because she's right, you’re not the real Cadence!”
The last to enter was the other Princess Cadence. Messy, but true, she walked alongside Twilight.
“You hypnotised my brother!” Twilight said.
“You trapped and impersonated the real Cadence!” Rainbow Dash said.
“You lied to everypony in the city!” Applejack said.
“What do you have to say for yourself, Chrysalis?” the other Cadence said.
Cadence knew the jig was up. She began laughing maniacally as she approached Twilight and her doppelganger. “You got me. You really got me. But you know what, you’re too late!”
Viridian flames surrounded the false Cadence as she levitated into the air. She was cocooned in a ball of green energy as her limbs and body became black and her mane became messy and a sickly teal.
The Changeling Queen, Chrysalis, had emerged from the cocoon and revealed her true form.
The reveal of Chrysalis’ identity shocked and repulsed everypony.
“The trojan horse has been opened,” Chrysalis said. “Your barrier is no more!”
Outside Canterlot, the changelings were attacking the barrier. They exploited the crack and weaknesses as they rammed into the magic sphere.
The barrier shattered and the pieces fell and disappeared. The changelings flew into the city.
Above, the windigoes, led by Diamond Dust, Apple Bloom, Sweetie Belle, and Scootaloo, flew into the city and began their feast.
From within the wedding hall. Chrysalis cackled madly as her forces had invaded Canterlot.
Twilight exclaimed, “What have you done to my brother?!”
Chrysalis approached Shining Armor and said, “You should have known. Didn’t you tell me that I ‘hypnotized’ Shining Armor?”
Twilight and her friends prepared to fight Chrysalis. Their battle had begun.