Gilles travels to the Arctic to find other trackers who may be able to help him. He discovers several distinct communities of people estranged from his technological age, then unexpectedly confronts E-Eddie on the pack ice. Piecing it all together, Gilles figures out that AIs have evolved. They're not just Artificial Intelligence, they are also Autonomous. They are A-AIs.

And they may have built an Ambit of their own. A Fourth Ambit.