Published in Detective Comics #15, May, 1938, 4 pages.
The mission for Bart Regan and Sally Norris is said to be their toughest assignment yet - the "task of apprehending 'Mr. Death', a madman who persists in killing international diplomats". Since no one has lived who could identify him, finding him seems impossible until Norris decides to taunt him into coming after her by placing an ad in evening paper insulting him and leaving her hotel address.