Serial had fifteen chapters, released in late 1919 and early 1920. All chapters were 2 reels with the exception of the very first chapter, which was three reels.
As of 2009, this film is considered to be lost.
Chapter titles: 1. The Great Secret 2. Marked for Death 3. The Gas Chamber 4. Below the Waterline 5. The Acid Bath 6. The Unknown 7. The Betrayal 8. A Crippled Hand 9. Woes of Deceit 10. The Inn of Dread 11. The Death Studio 12. The Chance Trail 13. Wings of Mystery 14. The Hidden Way 15. The Secret Host
Based on "In Secret" (1919), a story by Robert W. Chambers. This story blurb read, "American Intelligence at work on the eve of WW I.
What is the Great Secret? There was only one man in America who knew. And he had landed in New York that very morning. At that moment he was standing at the bar of the Hotel Astor, just sober enough to keep from telling everything he knew to the bartenders, and just drunk enough to talk too much in a place where the enemy always listens. Later he sauntered off on slightly unsteady legs to promenade himself in the lobby and Peacock Alley. Small wonder that his life was in terrible, terrible danger."