The ladder ended at a narrow level ledge of cold dark rock, three feet wide and six feet deep, tucked directly behind the inner top door beam of the Diamond Archive.
Above them, the ceiling was a solid vault of black iron plates heavy with cross-hatched bronze tie-rods. Directly in front of them stood the obstacle. The six-ton monolith slab of white novaculite, seamlessly fitted into its dark rock groove with a clearance limit of less than fifty hair-fractions. Not even a razor blade could be slipped between the stone door and the door post.
Ren Vale crouched on the ledge, his breathing shallow and disciplined, his right hand supporting his braced left forearm.
Beside him, Artificer Ren knelt on his felt blanket, reaching into his elk-hide tool-roll. He drew a long, slender tuning fork ground from cold gold-silver metal. He was stamped with the numeral 712. In his right hand, he raised his agate mallet.
“Twelve seconds,” the Artificer whispered, his face inches from the stone doorstep. “When the ringing latch trips, the high-pressure balance weights will hoist the slab upward into the ceiling recess. It will hold at maximum clearance for exactly twelve seconds before the balance tank refills and the slab drops. You must slide beneath the bottom edge on your right hip, keeping your braced arm tucked across your chest.”
