Mother knew she was really Tunneler 13. But Booker had said Mother was her nickname, which was sort of like a name—good enough for a library card, anyway.

Humming, she moved 300 meters down the tunnel, bored a hole 8 feet up the wall and packed it with explosives. Ishikawa had ordered her to do this under as much of the regolith as possible; why, she didn’t know. She did know why she’d been chosen; the top tier of tunnels had grown unstable, due to surface mining. The job was too dangerous for a human; but not for the newly minted republic’s Iron Lady.

She detected a tremor, and shielded her ports and sensors as part of the ceiling caved in. A silvery machine fell into the tunnel. It was man-shaped, but was larger and had more arms. Holsters for weapons and tools were arranged about its middle; more of them jutted directly from its body. The USNE three-circles insignia was prominent on its rounded top.

The last person she’d seen wearing that symbol was a mass-murderer.