Calpurnia Tate lives in Texas. She is only eleven, but she dreams of becoming a scientist. She made her first scientific discovery in a hot, dry summer. "Why are yellow grasshoppers much larger than green ones?" wondered Calpurnia. With the help of her grandfather, a self-taught naturalist, the girl begins to explore the natural world. Friendship with her grandfather helps her, the only sister of six brothers, to understand that the approach of the new, twentieth century opens up new opportunities for girls. But Calpurnia has yet to defend its right to study Nature, because the daughter of the owner of the cotton plantation is destined for the fate of his wife, mother, mistress of the house. But not a naturalist.