Sofia the First: A Promise is a Promise

Amber is looking forward to Hildegard's party until she learns that the royal visit with Prince Hugo's family is pushed to the same day, and that means she'll have to skip the party. However, Sofia may have to be absent because she's been summoned by the Secret Library to complete "The Tale of Sir Oliver"! But Amber talks Sofia into putting off her mission, so she can pose as her for the visit and Amber herself can go to the party. Amber doesn't think this can be dangerous, but can it?