Main character Meg Murry is worried about her brother Charles Wallace, a 6-year-old genius bullied at school by the other children. The new principal of the elementary school is the former high school principal, Mr. Jenkins, who often disciplined Meg, and who Meg is sure has a grudge against her whole family. Meg tries to enlist Jenkins's help in protecting her brother, but is unsuccessful. Later, Meg discovers that Charles Wallace has a progressive disease that is leaving him short of breath. Their mother, a microbiologist, suspects it may be a disorder of his mitochondria and his mitochondria's farandolae. (The farandolae are micro-organelles inside mitochondria that exist in the Time Quintet fantasy universe.)