Rarity is turned to a foal while visiting Manehattan and was kidnapped by Surie. Now she's trying to find her friends while going through the bustling streets of the big city
Rainbow Dash and some of the other recruits from the Wonderbolt Academy were regressed into toddlers. Now they have to relearn how to fly to escape the Daycare and find Twilight.
Hoity Toity is suddenly turned into a foal, and his collection of foal clothes went missing. Now he'll have to go to Manehatten and win a foal fashion show with the help of Rarity.
On the eve of Nightmare Moon's return three royal guards were transformed into toddlers. Celestia now has to raise these three foals and keep them in line.