With the help of her parents and her therapist, Amy learns that she has an Upstairs brain and a Downstairs brain.

Her Downstairs brain sometimes reacts in fear when there isn't anything to be scared of.

When Amy discovers a lost, frightened pet rat, she names her Pickles.

Pickles is fearful too, and as Amy tries to help Pickles, it further reinforces her understanding of her Downstairs and Upstairs brain.