In 1978, while collecting documentary photographs of the artists' community in Montparnasse from the first decades of the century, Billy Kluver discovered that some previously unassociated photographs fell into significant groupings. One group in particular, showing Picasso, Max Jacob, Moise Kisling, Modigliani, and others at the Cafe de la Rotonde and on Boulevard du Montparnasse, all seemed to have been taken on the same day. The people were wearing the same clothes in each shot and had the same accessories. Their ties were knotted the same way and their collars had the same wrinkles. A total of twenty-four photographs-four rolls of film with six photographs each-were eventually found. With the challenge of identifying the date, photographer, and circumstances, Kluver embarked on an inquiry that would illuminate the minute texture of that time and place.

Biographical research into the subjects' lives led Kluver to focus on the summer of 1916 as the likely time the photos were taken. He then measured buildings and plotted angles and lengths of shadows in the photographs to narrow the time frame to a spread of three weeks. Further investigation eventually allowed Kluver to identify the photographer as Jean Cocteau and to determine the day that Cocteau had taken the photographs: August 12, 1916. A computer printout of the sun's positions on that date, obtained from the Bureau des Longitudes, together with the length of the shadows, enabled Klver to calculate the time of day of each photograph, and thus to put them in proper sequence.

In a tour de force of art historical research, Kluver then reconstructed a scenario of the events of the four hours depicted in the photographs. With evocative attention to detail-noting when Picasso is no longer carrying an envelope or Max Jacob has acquired a decoration in his lapel-Kluver recreates a single afternoon in the lives of Picasso and friends, a group of remarkable people in early twentieth-century Paris.

Besides the central "portfolio" of photographs by Cocteau, the book contains additional photographs and drawings, short biographies of all the subjects, and a historical section on the events and activities in the Paris art world at the time.