Chapter Titles: 1. Agent of Treachery; 2. The Hidden Witness; 3. The Lost Tunnel; 4. Blades of Death; 5. Roaring Wheels; 6. Passage to Danger; 7. The Secret Code; 8. Doomed Cargo; 9. The Eyes of the Law; 10. The Stolen Body; 11. The Death Trap; 12. Talk or Die!; 13. Unmasked.