The Syren

First published in Thomson's Weekly News 05/04/1918
Heine is surprised and dismayed to learn during a visit by Major Haynes that the intelligence officer knows that German agents have a special sequence blown on a whistle to get all nearby agents to immediately report in. What that signal was, however, remained unknown and Heine is for certain not going to be the one to divulge it, no matter what Haynes tries.