The Counterfeiters: In the Paris Quarters

Published in Hearst's Magazine, Aug 1914. Collected in the book The Hand of Peril
Kestner is in Paris to help his colleague Wilsnach. That man is investigating a notorious forger and counterfeitor named Lambert and he is certain following that criminal's daughter, Maura, is the way to go. Kestner's attempt to break into their lair will not go well.
Note: we learn that "floating somewhere about the fringes of the gang" is a young American named Sadie Wimpel, living under the alias of Cherry Dreiser.