Synopsis by Hans J. Wollstein
As chapter seven of The Mystery Trooper reveals, Helen (Blanche Mehaffey) is not seriously wounded and her attacker is chased off by the Trooper. Jack, meanwhile, saves Mack (Charles King), who professes gratitude and undying support. It is all a ruse, however, and the villain instead lures Jack, Helen, Billy (Buzz Barton) and Red Eagle (William Bertram) to a cave filled with contraband. While the party discusses what to do next, the cave is dynamited by one of Mack's henchmen. Original chapter title: "The Day of Doom."