Destination: Imagination (3) (S06E08)

Feeling unappreciated for her hard work, Frankie comes across a mysterious toy box left at the entrance of Foster's. Though instructed to store it in the attic, her curiosity leads her to open it, revealing an imaginary friend trapped inside. Instantly, she is whisked away to a whimsical realm where a peculiar imaginary companion treats her like royalty. Meanwhile, Bloo, Mac, Wilt, Eduardo, and Coco realize Frankie's missing and embark on a quest to bring her back from this extraordinary world. This episode stands out as the only one rated TV-PG.