The Slaves of Paris by Emile Gaboriau

Had André known a little more of the man he had to deal with, he would have learned that no one could fall like an earthquake upon Van Klopen. Shut up in the sanctum where he composed the numberless costumes that were the wonder and delight of Paris, Van Klopen made as careful arrangements to secure himself from the interview as the Turk does to guard the approaches to his seraglio; and so André and Gandelu were accosted in the entrance hall by his stately footmen, clad in gorgeous liveries, glittering with gold.

"M. van Klopen is of the utmost importance," asserted André.