Blackfish City by Sam J. Miller

When the cities disappeared, those people who managed to survive all had to migrate to continue to exist.  They fled the destruction, the violence that decimated tribes and families.  Eventually, they ended up in the enclaves and cities that still existed; cities like Qaanaaq, an arctic city built around an oil rig.  Everyone lives in one of the eight arms; the arms vary in their space and amenities.  As is the case worldwide those with money inhabit the nicest arm and those with less are pushed further and further down the scale into arms ridden with crime and disease.

But something is happening.  The shareholders who rule the city due to their wealth and possession of the controlling software that runs the city are more and more remote from the rest of the people and know little of their lives and problems.  A new disease has arisen.  The breaks, as it is called, is sexually transmitted and those infected are swarmed with the memories and thoughts of those they contracted it from and those who that person got it from, a chain of memories and thoughts that eventually drive the victims mad.  The breaks is no respecter of place or money; it destroys everyone it contacts indiscriminately.

Then something even more unexpected happens.  A woman appears in the Northern Sea, riding an orca and accompanied by a polar bear.  Who is she?  Why has she come?  What will she do?  She is violent and is determined to meet her goals although those are not immediately clear.  She inserts herself into the emerging chaos of the battle between the shareholders and the criminal overloads and gathers a family around her.  Who will emerge victorious?

This novel was nominated as a Nebula Best Novel in 2018.  It is an original, highly entertaining and thought-provoking novel, one that the reader will remember long after the last page is turned.  The world building is superb, with a cold, uncaring world that seems likely after a worldwide destruction yet the people who survive still search for meaning and connection.  The last ten percent of the novel are as stunning a resolution as I can remember reading.  This book is recommended for science fiction readers.