To Your Scattered Bodies Go

Mostly fantasy, and a little sci-fi... To Your Scattered Bodies Go is told in episodic chapters. It is the 1st of 5 books in the Riverworld series.

Everyone who has ever lived on earth wakes up on the banks of a seemingly endless river. They are young and whole. They remember their lives on Earth. On Riverworld, our characters learn to adapt, survive and explore. It's obviously not heaven, and not hell. Burton wants to know why is this happening?

It's worth reading, although I'll have to read the other books, hopefully, to get a complete explanation.