Each time it flew a certain distance, the surface of the gray mist would occasionally ripple with an extremely subtle circle, expanding outwards from a certain point into the depths of the mist layer, before returning to silence.
The direction of those ripples seemed to follow a certain pattern, but the bird's field of vision was too narrow to see the bigger picture.
After spending an hour conducting careful research and investigation, Duke confirmed that it was impossible to traverse the top of the high walls.
He withdrew his eye of exploration and turned to look around at the boundless gray-white stone corridor.
Since he couldn't break through upwards, he could only move under these high walls.
He walked to the nearest stone wall, pressing his hand against the rough gray-white stone slab.
