The fairy princesses' friends are having a party in Glitter Ocean. They're so excited and set off in a pearl-encrusted shell boat, wearing full-length mermaid gowns. But then the boat gets caught in a glitter storm! Luckily, Buttercup calls out to some friendly seahorses, who give the fairy princesses a ride to the Coral Castle deep in the sparkly sea. But their clothes have been ruined on the hazardous journey! Can the sea fairies help get them ready for the party in time?