Annabelle and Tiffany, dolls who are best friends living in the Palmer house, have an adventure when they hide in Kate Palmer's backpack, are carried to school, mistakenly go to another house, and try to stop Princess Mimi, a doll who threatens all dollkind.

Best friends Annabelle and Tiffany risk placing all of dollkind in danger when they run away while trying to prevent Tilly from being sent back to London before they can determine if she is Annabelle's long-lost baby sister.