Abbie Gascho Landis first fell for freshwater mussels while submerged in an Alabama creek, her pregnant belly squeezed into a wetsuit. After an hour of fruitless scanning, a mussel materialized from the rocks—a little spectaclecase, herself pregnant, filtering the river water through a delicate body while her gills bulged with offspring. In that moment of connection, Landis became a mussel groupie, obsessed with learning more about the creatures' hidden lives. She isn't the only fanatic; the shy mollusks, so vital to the health of rivers around the world, have a way of inspiring unusual devotion. In Immersion: The Science and Mystery of Freshwater Mussels, Landis brings readers to a hotbed of mussel diversity, the American Southeast, to seek mussels where they eat, procreate, and, too often, perish. Accompanied often by her husband, a mussel scientist, and her young children, she learned to see mussels on the creekbed, to tell a spectaclecase from a pigtoe, and to worry what vanishing mussels—70 percent of North American species are imperiled—will mean for humans and wildlife alike. In Immersion, Landis shares this journey, traveling from perilous river surveys to dry streambeds and into laboratories where endangered mussels are raised one precious life at a time. Mussels have much to teach us about the health of our watersheds if we step into the creek and take a closer look at their lives. In the tradition of writers like Terry Tempest Williams and Sy Montgomery, Landis gracefully chronicles these untold stories with a veterinarian's careful eye and the curiosity of a naturalist. In turns joyful and sobering, Immersion is an invitation to see rivers from a mussel's perspective, a celebration of the wild lives visible to those who learn to search.