Two boys, Ellis and his best friend Neckbone, find a mysterious man named Mud hiding out on a deserted island in the Mississippi. Mud tells the boys fantastic stories about his life, including how he killed a man in Texas and vengeful bounty hunters are coming to get him. He says he is planning to meet and escape with the love of his life, Juniper. The boys agree to help him, but it isn't long until their small town is besieged by bounty hunters out...

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.