“The Adventure of ‘X’”
Published under the pen name Ken Martin

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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.