In March 1949, Robert Frank mailed a birthday gift to his mother in Switzerland: A maquette of a series of photographs he had made during a visit to Peru between June and December of the previous year. Frank assembled an identical book for himself, and these two maquettes now reside in the collections of The Museum of Modern Art, New York and the National Gallery of Art, Washington. A few of the images are well known in Frank's oeuvre, but until now very few people have seen the entire series--which, in 1949, already displayed the hallmark of Frank's distinctive image-sequencing. Peru...