Grace is back to her zany antics again! Grace and Mimi have a secret: Mimi is going to be a big sister. To get ready, the girls try being "mother's helpers" to a family down the street, and Mimi begins to doubt her big sister abilities when 4-year-old Lily seems to like Grace best. But when Lily turns into a Terrible Tutu, Grace can't escape her! Can Grace use her empathy powers to shows Lily and Mimi the creative path towards a new friendship?