It was not long after he had moved to Paris in 1921 that Vertès was introduced to the author Pierre Mac Orlan, and it is easy to see why the two men found interests in common; in 1925 Mac Orlan asked Vertès to illustrate his new novel of Parisian brothel life. It was published anonymously in 1926 by the publisher Paul Cotinaud, with seven coloured illustrations by Vertès.

The critic Patrick Grainville has written of La semaine secréte, ‘Mac Orlan oscillates between sex which is raw to a fault, and that which is bold and feisty, not wanting to miss a thing. He sails the borderlines between the street and the brothel, the modern secretary and the archaic catina of the Orient, between the orgy and the individual, between boldness and shame, between public exhibitionism and private revelation. There is in this Mac Orlan volume a background noise of sex, a whole landscape, a physical paradise.’