Meg Murry can't help but be worried when her six-year-old brother, Charles Wallace, announces there are dragons in the vegetable garden. He's so bright, and so different from other kids, he's getting bullied at school, and he is also strangely, seriously ill.

But Charles Wallace is right about the garden, although the dragon turns out to be a cherubim named Proginoskes who has come to help Charles Wallace fight his sickness. Saving Charles, it turns out, is the only thing that can save the universe.