Part memoir, part travelogue, part history of the foghorn, this is a booming, lonely sound echoing into the vastness of the sea. When the author hears the foghorn's colossal bellow for the first time, it marks the beginning of an obsession and a journey deep into the history of a sound that has carved out the identity and the landscape of coastlines around the world, from Scotland to San Francisco. Within its sound is a maritime history of shipwrecks and lighthouse keepers, the story and science of our industrial past. The book is an odyssey told through the people who battled sea and sound, who lived with it and loathed it, and one woman's intrepid voyage through the howling loneliness of nature.