Chapter titles: The Violet Diamond; The Crushing Walls; Borrowed Identity; The Warning on the Ring; Danger Underground; Rays of Death; The Signal Lantern; The Switch in the Safe; The Dice of Death; The Perilous Plunge; The Short Circuit; A Desperate Chance; A Dash of Arabia; The Painted Safe; The Dagger Duel; The Double Disguise; The Death Weight; The Subterfuge; The End of the Trail.