Princess Cadence tells her side of the story of how she and Shining Armor met. When she foal-sits Twilight Sparkle, she asks the young filly for help to make him her very special pony. Unfortunately, before Shining Armor can ask her to the dance, another pony asks Cadence first.
Reunited in friendship, the ponies reach the stronghold of Queen Chrysalis, where a display of Twilight Sparkle's power causes the Queen to change her goal. Instead of draining Twilight's power, she now wants Twilight to join her, and Twilight agrees, but only to save everyone else.
Although they have made it through the mountain, the Mane Six are at odds with each other and have split into three groups. Without the Power of Friendship, how will they save the litle ponies?.
When everybody starts acting strange, Pinkie Pie, Rainbow Dash, and some of the others realize that ponies are being replaced by changelings and they manage to save the town, but find that Sweetie Belle, Apple Bloom, and Scootaloo are missing.