Robert Sullivan's book "Double Exposure" delves into the American West through the lens of war photographer Timothy O'Sullivan. Known for iconic Civil War images like "A Harvest of Death," O'Sullivan elevated photography to fine art while capturing the West during the Clarence King and George Wheeler surveys. Despite his significant work, little is known about O'Sullivan or the landscapes he photographed. Sullivan embarks on a journey retracing O'Sullivan's steps, exploring forgotten sites, and examining the transformation of the American landscape post-Civil War. The book captures this ongoing change, echoing O'Sullivan's own profound images.