The story opens with a mysterious telegraph instrument unearthed in the desert that hints at an inaccessible inner world; an impulsive expedition follows the signal into a vast hollow realm where primeval landscapes, enormous creatures, and rival human groups pose constant danger. Episodes alternate travel and intense action—stranding, capture, prison raids, desperate flights, and daring rescues—culminating in large-scale conflict and eventual settlement. Throughout, the narrative foregrounds survival, the wonder of undiscovered domains, shifting loyalties, and the tension between force and conciliation.