In 2210 Herb discovers his illegal self-replicating city-building machines have gone terribly wrong. In 2051 Eva plots her escape from the stultifying Social Care service. In 2119 Constantine, a "ghost" agent invisible to monitoring, wonders if he is going mad from the isolation. These three plot strand weave together to expose a presence that may mean the end of humanity, or worse, be its saviour.
The ideas are interesting --- taking the existence of self-replicating machines and super-intelligent AIs and showing how they do, and don't, change things ---along with a dash of Fermi Paradox. But I found the characters, particularly the pathetic Herb, very unappealing, and the final resolution a combination of let-down, and problematic. The fact that one of the characters speculates for half a sentence on this problem doesn't really help.
So, a good SFnal premise, but nothing earth shattering.