This is the second book in the Murderbot diaries here is my review of the first one All systems red.
Plot
Having left the people who bought Murderbot from the Company, they they decide to travel to the mining station were it all began. Where it hacked themself, went on a killing spree and named themself Murderbot, not necessarily in that order. To get there they hitch a ride with ART a research ship far more intelligent than they thought who insists on helping Muderbot after some threats.
At the mining station they take a job as security guard to get a travel pass. Working for a group of researcher trying to get back data that was stolen from them. something that turns out to be just as dangerous as Murderbot thought it would be.
My thoughts
The friendship between Murderbot and Art is one of the highlights. Basically ART (not their name it's just what Murderbot calls them) is a bot piloted ship owned by a university. They are a know it all, giver of unwanted advice and the extroverted friend Murderbot needs.
In the first book Murderbot only interacted with humans which they did as little as possible. In this one though we see them interacting with a lot more bots, besides ART there is a Comfortunit (similar in structure to Secunits like Murderbot but without the weapons). Murderbot tells Art that bots can't trust each others since they always have to obey humans orders. Despite this its clear that they do trust bots more than humans probably because they can't force them to do something.
I kind of like that the mystery of what happened to make Murderbot free themselves was so pointless. There was no great conspiracy just people being greedy and underestimating dangers, stupid choices that lead to horrifying consequences.