Growing up can be a bumpy road, and it's no exception for Riley, who is uprooted from her Midwest life when her father starts a new job in San Francisco. Like all of us, Riley is guided by her emotions ; Joy, Fear, Anger, Disgust, and Sadness. The emotions live in Headquarters, the control center inside Riley's mind, where they help advise her through everyday life.

Although he has been missing for several years and the entire town thinks her father has abandoned her family, Meg steadfastly believes the best and protects her younger brother, Charles Wallace, from the brunt of the rumors and taunting. It is he, however, who convinces her to join him, the school sports star Calvin, and three unusual women on an interplanetary voyage to rescue their father from a vast evil.