When a childless couple buries a box with all of their wishes for an infant in their backyard, their wishes are granted. However, their child, Timothy Green, is not all that he appears.

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.