“The Adventure of ‘X’”
Published under the pen name Ken Martin
Publication date: November 1935
Original publication: Top-Notch
Genre: Military & War
Story description: An ex-US Army Lieutenant, now a Legionnaire with a chip on his shoulder, is freed from prison only to be sent on a deadly intelligence mission into hostile territory.
Currently available as part of the Stories from the Golden Age series, in the title Fifty-Fifty O’Brien.