It’s not terribly unusual for a boy to have an imaginary friend, but Matthew’s parents have to agree that his—nicknamed Chocky—is anything but ordinary. Why, Chocky demands to know, are there twenty-four hours in a day? Why are there two sexes? Why can’t Matthew solve his math homework using a logical system like binary code? When the questions Chocky asks become too advanced and, frankly, too odd for teachers to answer, Matthew’s parents start to wonder if Chocky might be something far stranger than a figment of their son’s imagination.

Chocky is a playful investigation of what being human is all about, delving into such matters as child-rearing, marriage, learning, artistic inspiration—and ending with a surprising and impassioned plea for better human stewardship of the earth.