In "Twins," Mark turns her eye and her heart to the extraordinary bond that exists between these very special siblings. For two years in a row, she set up a studio on the site of America's premier twins festival and invited participants to be photographed. Using a twenty-by-twenty-four-inch Polaroid camera, Mark created an extraordinary body of work-a collection of sometimes beautiful, often unsettling images-that reveals subtle nuances in the relationships of the twins she observed. Gorgeously printed in tritone, the book replicates the stellar quality of her large-format photographs in a fitting tribute to one of America's preeminent photographers.