In this book Sacks takes the reader into the world of the prelingually deaf, a world in which spoken language is incomprehensible. He describes the visual language, Sign, and considers the development and culture of American Sign Language. Sacks evokes the conflict between those who seek to teach the deaf to communicate via voice and lip-reading and those who affirm Sign, the native culture of the deaf.

In the latter part of the book, Sacks re-creates the student rebellion at Gallaudet University in 1988 when a "hearing" president was chosen from among three finalists, two of whom were deaf. The back cover summarizes this book as "a provocative meditation on communication, biology, and culture."