The Temptress by William le Queux

Midnight in Brussels. Six months had passed since Valerie's hurried exit from Paris had baffled the most expert member of the Paris detective force.

The streets were quiet, almost deserted; the trees in the boulevards were stirred slightly by the soft wind, and the long lines of gas lamps flickered and cast an uncertain light as Pierre Rouillier, in evening dress, and with an Inverness cape about his shoulders, emerged from the Rue de Pepin, crossed the boulevard, and turned into the Chausee de Wavre. Whistling softly to himself, he continued his walk down the long, straight thoroughfare until within a few yards of the Rue Wiertz, where, before a large and rather gloomy-looking house, he halted. He gave two vigorous tugs at the bell, and Nanette opened the door.