As Nightmare moon laughs evilly and flies away, Twilight returns to the library searching for more information about the Elements of Harmony while Applejack, Fluttershy, Pinkie Pie, Rainbow Dash, and Rarity follows. They locate a book called: The Elements of Harmony: A reference guild which tells them there are 6 elements and they are: Kindness, Laughter, Generosity, Honesty, Loyalty, and an "unknown element triggered by a "spark". The Elements are located in a castle in the Everfree forest, a place where weird things happen. As the ponies plan the trip, Nightmare Moon in the form of a cloud overhears them talking and gets a head start for the Everfree Forest.
Nightmare Moon, the one who caused the avalanche, turns into a thorn and sticks herself into a manticore's paw. The group, who later stumbles across the manticore, fights it but they couldn't let the manticore let them pass. Fluttershy who was in the background yells for them to stop but since her voice is so timid they don't hear her until she screams. Right after Fluttershy comes up to the manticore, the rest of the group looks away as Fluttershy takes the thorn out. After they find out she's okay, Twilight asks her how did she knew and she replied "Sometimes you just got to show a little kindness"
After wandering into a darkened area of the forest, the group are frightened by trees carved with scary faces. ( This was Nightmare Moon’s doing.) However, Pinkie just laughed and made funny faces, causing the faices to vanish. Singing a song, Pinkie explained to them that if you laugh your fears will vanish. After laughing for a while, they move on.
Coming to a river, the group encounters a flamboyant sea serpent, deeply upset by having his mustache ruined as a "cloud of tacky, purple smoke" went by and cutting half of it off.( Again, Nightmare Moon did it ) Rarity, angered by this "crime against fabulousity" sympathies with him and cuts off her own tail so that his moustache can be restored. The sea serpent then calms down, allowing the ponies to cross the river on his back.
The ponies enter the castle ruins and come to stand in front of several stone orbs perched on a pedestal, which Twilight assumes are the Elements of Harmony. Dash and Fluttershy place them at Twilight's feet, and Pinkie notices there are only five of them. Twilight explains that when the five are present, a spark would cause the sixth to be revealed. The rest of the ponies leave as Twilight tries to use her magic on the orbs, but the purple mist appears and envelops them in a whirlwind. Twilight jumps in and disappears along with the purple mist. The other ponies see glowing lights in another part of the ruins and head to it. Twilight and Nightmare Moon re-appear at opposite ends of a large hall, with the stone orbs around Nightmare Moon. Twilight stamps her hoof and charges at Nightmare Moon, leading her to do the same.
Right before they collide, Twilight disappears, then reappears next to the orbs. She tries to use her magic to create a spark, but Nightmare Moon turns into mist and rematerializes in front of her, and blasts her away from the orbs. For a moment the orbs sparkle and frighten Nightmare Moon, but they soon stop, allowing her to shatter them by stamping on the ground. Pleased with this, Nightmare Moon declares victory, swirling her purple mist around herself.
Then, Twilight hears her friends calling with reassuring words, and something sparks inside her. She gives Nightmare Moon a speech on the Elements of Harmony, declaring the spirits of the Elements of Harmony are "right here", as the other five ponies arrive behind her. The stone fragments glow and float around each pony as Twilight explains which element each of them represents based on their actions during their journey. Nightmare Moon protests, saying they don't have the sixth element, but Twilight tells her a different kind of spark revealed the sixth element, the spark that she felt when she realized the five other ponies are her friends.
When Twilight concludes the speech, the fragments turn into jewels, and the six ponies glow and float in the air as a rainbow emerges from them and covers Nightmare Moon. Twilight opens her eyes, which floods the room with bright white light. Once the light fades, the ponies discover that Rarity's tail is restored, and that they all have jewelry that matches their cutie marks.
As the sun rises, Princess Celestia appears and explains that she knew Twilight had the magic to defeat Nightmare Moon, but she could only unleash it by letting true friendship into her heart. They soon see a smaller winged unicorn that was Nightmare Moon before Twilight defeated her. Princess Celestia recognized this pony and called her Princess Luna, who she was before. She wears a dark blue crown and a coat and mane in a lighter shade of violet and blue. Princess Celestia offers her sister the friendship they were supposed to have all along. Luna accepts the offer and Princess Celestia, happy to see her sister again, she embraces Luna in a tearful reunion. Back in Ponyville, Pinkie throws a party to celebrate the reunion of the two Princesses - but Twilight looks sad. When asked why, Twilight tells Celestia she's sad of leaving her new friends and returning home, so Celestia issues her with a new mission: study the magic of friendship in Ponyville, and report her findings. Twilight is happy about being able to stay with her friends and promises to study harder than ever before.
