Several miles off the Mississippi coast, Horn Island rises out of the sea. A wilderness of slash pine, sea oats, and osprey, the barrier island stirs the imagination, nourishes the spirit, and challenges the soul. It is as unforgiving as it is lovely, with a story that unfolds as a natural pageant of sand, water, and wind.

Walter Anderson, artist and naturalist, fell under Horn Island's spell and painted myriad water-colors of its crabs, fish, birds, and butterflies in some of his most vivid and memorable work. Anderson's retreat and April Newlin's refuge weave together in a rich and...