The city of Ossa hung suspended within the ribcage of a long-dead leviathan. For three centuries, humanity had built its homes along the curve of colossal, ivory-white bones, stringing bridges of iron and rope across the vast, empty cavern of the creature's chest. Up high, near the spine, the wealthy lived in manors carved directly into the fossilized marrow. Down below, where the ribs met the perpetual fog of the Chasm, lived the scavengers, the miners, and people like Elara.
Elara was a cartographer of the forgotten. Her workshop was a cramped, ink-stained room clinging to the underside of the seventh left rib. She spent her days cataloging the ever-shifting tunnels carved by marrow-miners in the beast's lower half.
It happened on a Tuesday, late into the evening. Elara was attempting to restore a crumbling, illegible map recovered from the deepest mining tier. Frustrated, she pushed the parchment aside, accidentally knocking over a vial of lunar-dust solvent. The silver liquid spilled across the cracked leather of the map.
She cursed, scrambling for a cloth, but stopped abruptly. Where the solvent soaked into the leather, the old, faded ink did not wash away. Instead, it drank the silver liquid in. As the moonlight from her window struck the damp surface, the map began to glow.
New lines bloomed across the parchment—not tunnels carved by men, but ancient, pulsating veins. They all converged on a single, massive chamber deep within the Chasm, far below any known mining tier. Beside the chamber, written in an archaic script Elara could barely decipher, was a single word: The Primer.
The leviathan wasn't entirely dead. Its heart, or whatever functioned as its heart, was still down there. And according to the glowing silver lines, the pathways leading to it were beginning to collapse. If the lower tunnels collapsed, the ribs would follow. Ossa would fall.