(spoilers below the image)
The book consists of multiple distinct large parts on a timeline. Normal beginnings where a billionaire wants his body preserved until his brain can be properly scanned, a part where the internet is becoming obsolete due to too many fakes, hoaxes and trolling, a post truth US where religious cults are rampant in Ameristan i.e. the spaces between the urban areas that are still tied to reality, the part where the rebooted brain of the billionaire creates his own world, to be unseated as main deity by newcomers, and a quest to right that wrong.
Enoch Root makes an appearance again, entering quite dramatically, and seems to indicate he comes from a plane of existence that created our world as a simulation. Towards the end Zula says ‘I understand light speed now’ as an externally applied constraint, the limit posed by the processing power available to our virtual environment. The speed at which changes propagating from an event can be calculated determines the speed of causality in the piece of spacetime we’re in. That’s the moment Enoch Root says to her his task here is complete and he vanishes into the fog, suggesting he’s leaving our sim, to return to another plane of existence. Not so much turtles all the way down, as sims all the way up?