Akira is getting bored with his unsuccessful searches for unknown artifact caches and together with Alpha they decide to explore a known location. It doesn't take long before things go haywire. The site is run by an Old World maintenance system, usually very predictable (still deadly), but the murder robots start acting off script.
As always, solid world building: not many info dumps and those that come feel natural with Akira asking the questions, and also some subtle hints in there that things are not as they seem such as for example Akira's questions to Alpha about why simple office building guards are so lethal. It is certainly an unique setting as far as light novels go. Love the characters and their development, and hooked on what exactly Alpha and her compatriot's real goals are.
It was somewhat difficult for me to get invested in the story though: maybe some aspects are getting a bit too repetitive for me? Go in ruins, goes fine for some time, trigger a problem, deal with monsters, rinse and repeat. Mind you, I am not a big fan of action and I do get bored quickly with long fights, and while some of the boss fights were great (not as long as some in earlier volumes), the minion fights felt the same. The main plot does progress, but very slowly, but only through indirect hints. I really want some more answers.
O well, in the end I did enjoy the story, and I am hooked on the mystery, characters and world.