Mara paused at the threshold, glanced back, and said, "Doctor. Last chance to go back up and explain to your sky friend why you nearly got peeled open for a theory."

Lina flashed through his mind: waiting at the edge of light, refusing to leave, fear wrapped around loyalty so tight they looked the same. He would have to find a way back to her if he lived long enough to regret this properly.

"I'm coming," he said.

Mara gave one short nod. Kellen slid the mesh aside for them and the hidden nest fell behind. Ahead, the machine levels breathed long cold drafts into the dark. Somewhere deeper in the tunnels a tone rose and fell, not music, not warning exactly, something in between. Mara took the first turn without slowing, Elias went after her, and with each step the bought map in her jacket and the silence behind them felt more and more like a message already on its way to someone else.