All the youth of Mewni gather at the ancient Monster Temple to celebrate a new era of monsters and Mewmans living together in peace -- until guests start disappearing.

Ponyhead returns to St. O’s and finds that the curriculum got tougher.

Eclipsa and Moon bring Princess Meteora home peacefully after the massive destruction she's caused.

Star becomes acting Queen and plans for Marco and his warriors to delay Meteora from reaching Castle Butterfly long enough for Star to find Moon and destroy the monster princess.

Star must find the courage to face Meteora alone and make a decision that will change the kingdom forever.