Ahead of me the tunnel opened into a wide chamber, and I saw the white form of Vertorix glimmer momentarily in the semidarkness and vanish in what appeared to be the entrance of a corridor opposite the mouth of the tunnel I had just traversed. Instantly there sounded a short, fierce shout and the crash of a hard-driven blow, mixed with the hysterical screams of a girl and a medley of serpentlike hissing that made my hair bristle. And at that instant I shot out of the tunnel, running at full speed, and realized too late the floor of the cavern lay several feet below the level of the tunnel. My flying feet missed the tiny steps and I crashed terrifically on the solid stone floor.