In writing this book, author, naturalist, and educator Steve Ramirez traveled thousands of miles by plane, motor vehicle, boat, and foot. Each chapter includes his fishing with a notable person in the worlds of fishing and conservation. His fishing partners in this book include Bob White, Chris Wood, Kirk Deeter (and many other leaders within Trout Unlimited), Ted Williams of The Native Fish Coalition, Matthew Miller, and John Karges of The Nature Conservancy, and many more.

In the course of this journey, Ramirez explores and fishes mountain streams, alpine lakes, National Wild and Scenic Rivers, desert canyons, brackish water estuaries, and the rolling ocean off the coast of Cape Cod. About half of this book was written while traveling through the COVID-19 pandemic and it touches on the lessons that COVID can teach us about nature and human nature.

In Casting Onward, the author expands beyond the geographical scope of Casting Forward by fishing for native fish within their original habitats across American. Each story is told in part through the eyes of the people who have lived alongside and come to love, these waters and fish. Woven throughout these adventures are the stories of the people he meets and befriends while pursuing a mutual love of nature and the best of human nature, as the first criterion for finding common ground.

This is a hopeful story, in an all-too-often seemingly hopeless time. It is a story of fishing and friendship. It is a story of humanity's impact on nature, and nature's impact on humanity.