Genetically engineering lifted psychic powers above the random background of coincidence. Backlash and prejudice against 'magic' and 'demons' resulted in the exile of the genetically engineered to dangerous worlds, not-quite-parallel earths they weren't expected to survive.
Thirteen centuries of turbulent Earth history later they've been forgotten.
While the first book in this series covered the development of powered people and their exile to alternative Earths, the second and third books take place entirely on one of the exile planets. There, the powers of the gods have continued evolving through genetic mixing as people had children over the next 1360 or so years.
This book, the fourth in the series, is about what happens when the people of old Earth reopen a gate to the planet where the gods and their descendants have been living.
I think what kept me from giving this a 5 star rating is that the people from Earth, in the year 3477 or so don't seem any different from us in 2016. Their technology has hardly advanced considering how long they've had to develop it. Socially, they are just as stupid as we are today. I would have hoped that there would have been a bit more social evolution. Instead, they are just as willing to exploit the "primitive" cultures they encounter and use force to ensure they get what they want. That's kind of depressing. Still, I'm anxious to see what happens in the next book.
This story continued with a group of the characters from the last book, and added in some characters from Earth. It was fun to watch what happened when the former exiles encountered people from their homeworld, and vice versa. We got to see the unfolding events from both perspectives, and it was fun to explore, through their eyes, both the world of the series, as well as several other dimensional worlds, as well as the future Earth.
This ended the immediate story but definitely left it open for future possibilities -- you know that Earth isn't going to be able to leave them alone forever!
An enjoyable addition to the series and I was pleased to meet some new characters in these worlds.