Mademoiselle of Monte Carlo by William le Queux

At ten o'clock on the morning that Hugh Henfrey left Avignon for Paris, The Sparrow stood at the window of his cozy little flat in the Rue des Petits Champs, where he was known to his elderly housekeeper -- a worthy old soul from Yvetot, in the north -- as Guillaume Gautier.

The house was one of those great old ones built in the days of the First Empire, with a narrow entrance and square courtyard into which the stage coaches with postilions rumbled before the days of the P. L. M. and aircraft. In the Napoleonic days it had been the residence of the Dukes de Vizelle, but in modern times it had been converted into a series of very commodious flats.