On a volcanic colony world, atmospheric processor towers were built to scrub ash and glass-sleet from the evacuation lanes so shuttles could land and lift off through the poisoned sky.

Now the ridge-hatchets have taken the high ground. These giant predatory birds nest inside towers, sensor masts, and ventilation shafts, blinding the colony’s systems while using cloud cover and vertical terrain to kill anything moving below.

Firebase Anvil is trapped under the ash ceiling, its evacuation window closing. A combat engineer team crosses an ash-choked ravine to restart Spire Seven and clear the lane. But inside the processor, the ridge-hatchets have packed the vents with nests made from stick, cable, animal remains, military kit, and human limbs — and the adult bird is still above them, listening through the tower.

This is "The Bone  ...