The Big Shrink will be the sixth book in the Upside-Down Magic series. Little about it is known.
Little is known about Book #6. However, from the title, it can be presumed that Marigold plays a role. On her 2018 tour, Sarah Mlynowski, one of the authors, was asked about the book by a fan. She describes a new trend, a toy called a greg. The teachers do not allow gregs in the classrooms. Students protest by being shrank by Marigold. The cover features Nory in her dritten form on a school lunch tray.