Exploring the night and the effect it has on the human race, this series of essays begins with mankind's quest to light up the night. It continues by questioning what happens when we sleep, why we dream and what language we dream in. The study ends with night in modern cities - how we make darkness safe, and how we inhabit it. Alvarez visits a sleep laboratory, spends a night on a mountain and another in a New York squad car. He gives an understanding of the language of dreams and an explanation of how dreams affect our waking selves.