On Secret Service: The Secret Coast-Gun
Written by
Arthur Stringer
Copyright 1915
Published in Hearst's Magazine, Jul 1915. Collected as chapters 4-7 in the book
Working under orders from Kestener, Wilsnach and Sadie Wimpel launch an attempt to capture spymaster Keudell and a man named Dorgan who has stolen the plans for a revolutionary naval coast gun.