Twilight, Pinkie Pie, Rainbow Dash, and Rarity magically enter the books to try to stop the bookworm and repair the damage but become sidetracked when they find themselves enacting various stories and over-embellish the original tales.
Discord understands that he still has much to learn about being a good friend and returns the group to the present day, first making sure that Fluttershy gets to see the beauty of the prehistoric creatures.
King Aspen points out how part of the forest is being razed by the minotaur business tycoon, Well-To-Do, for the construction of a theme park, and his activities have rendered the plants nearby unable to grow, and so they see their actions as taking back what is rightfully theirs.
The sheer size of the crowd quickly overwhelms the town, throwing all the events into chaos, and Twilight begs everypony to help each other out as best they can so that the visitors will be happy.
As the festival draws to a close, Twilight presents a plaque to each of them - one to mark Ponyville's first residence at Sweet Apple Acres, the other for its first commercial building at what is now the Carousel Boutique.
However, as she is still unstable, they secure Flutterbat under the watchful eyes of the Cutie Mark Crusaders, and Twilight uses a spell to transform herself and the other Mane 6 into vampire bat ponies, with more control of their sense.
Twilight senses the magic from Celestia and Luna's battle centuries ago and uses some of it to super-charge Spike's fire breath, which he uses to power Pinkie's party cannon to launch the meteor into the depths of space.
The Mane 6 decide to split up and protect various places that Shadow Lock could strike next: the Ponyville schoolhouse, a Canterlot newspaper, and a Colonial Whinniesburg re-enactment.
Lily is horrified by this and privately explains to Scootaloo her fear that her cutie mark will not help her represent Canterlot's social elite as Fancy Pants wishes.
Weeks later, the CMC are invited to a fundraiser at the Canterlot Observatory hosted by Lily and Fancy Pants, while Scootaloo prepares for the first Extreme Sports Cutie Mark Camp, accompanied by her fellow crusaders.
As the Convocation begins, Raven and the aides to the other species' leaders go to work updating the extensive document archives in the library of the meeting hall, choosing to ignore what they see as a boring political summit.
With the crisis resolved and Goldstone arrested on charges of treason, the Equestrian delegation returns home; Raven promises to keep in touch with the other archivists and decides to leave the adventuring to Twilight and her friends.
After a number of stops, she arrives in Ponyville, only for her amulet to be stolen by a filly named Scarlet Petal, leaving Celestia trapped in her powerless Pegasus form.
Discovering a trail that seems to lead to the perpetrator of the recent troubles, Tempest pursues it on her own only to run into an Ursa Minor, the same type of creature that broke her horn.
Enraged to be saved by the pony she feels abandoned her, she nearly attacks Glitter Drops, who then tearfully admits to having carried the guilt for Tempest's broken horn for years.
Seeing how bored everypony is, Rainbow invents a variant called "Extreme Bingo," hiding the number balls all over Ponyville for the Gals to find so they can fill out their cards.
Realizing that she's being affected by magic, Twilight goes to the library with Spike for research, while Applejack, Pinkie, and Rainbow head to Fluttershy's cottage, where they find Zephyr Breeze and tell him what is happening.
Twilight deduces that Fluttershy is being affected by the Animalulet, a long-lost relic created by Star Swirl the Bearded and she and Spike ask Rarity to help find it.
Pinkie and Big Mac head to Klugetown, Rainbow, Rarity, and Spike to the Crystal Empire, Zecora and the Cutie Mark Crusaders to Griffonstone, Fluttershy to the Everfree Forest, and Applejack and Twilight to Canterlot.
At Canterlot, Twilight ignores Applejack's suggestion at telling Celestia and Luna about what they're doing and heads to a secret underground chamber housing several forbidden artifacts, one of which is the second Andalusian star.
The two quickly bonded over their shared love for chaos and wreaked havoc across Equestria, with Discord keeping the princesses busy with illusions so that they wouldn't interfere.
His commander, Captain Ironhead, brings news that an accident at the weather factory has created a massive storm that is currently drifting over griffon territory toward the city.
Ironhead orders his team to retreat back over the border, but Flash defies him and leads the other three in a rescue effort to save the young griffons in a village about to be hit by the storm.
While visiting Fluttershy, however, the Crusaders learn that it is nesting season for the Equestrian social weaver bird, and between this and feathers seen near a small window in the supply closet deduce the truth.
They question Diamond Tiara, whose father Filthy Rich wants to put up a hotel on the site, and resident Sand Trap, who had criticized the Retirement Village in the past.
Fire Streak berates the Crusaders for risking their safety, but the residents thank them and Holiday and Lofty organize a "throwback" Filly Guide outing with Pearly as their guest.
The Crusaders discover that Flim and Flam are in town selling hybrid fruits, and another check of the pipeline reveals an additional buried section that leads to their tree.
When Pinkie Pie tries to defuse the situation with a joke, Blueblood derides her humor, annoying her to the point that she tells Nightmare Moon to be quiet so she can scold him.
Twilight and Applejack wander to Sweet Apple Acres, where they see the three enjoying the company of Granny Smith and Big McIntosh, and realize that their insistence on tradition and factual correctness has caused the rift.
All twelve are able to open the portal by working together, whereupon Princess Celestia arrives and casts a spell to erase everypony's memories of the day in order to avoid any damage to the timeline.