2018’s Deep Roots is the second volume in Ruthanna Emrys’ Innsmouth Legacy series.
Aphra Marsh survived an American concentration camp. She is one of very few land-dwelling Deep Ones still alive. Despite their much reduced numbers, she hopes to rebuild her shattered community. To do this, she needs the US government’s cooperation — or at least an end to active attempts to exterminate the Deep Ones.
But nuclear war threatens. Were it to happen, it would render her efforts pointless. Toleration of land-dwelling Deep Ones would mean nothing if the humans were to make the land temporarily uninhabitable. The ocean-dwelling Deep Ones would live on, but once their land-kin vanished, there would be no way to re-establish them.
The Deep Ones are not the only beings worried about humanity’s future.