The plot concerns mathematician Felix Rayman, whose bizarre out of body experiences are nightmarishly related to his research into Cantor's continuum hypothesis. Now, I'm not sure exactly how much this is really autobiographical, but Rucker admit's in the "afterword" that he actually had a position at the university described in the book, and that his own attempt to address the continuum problem led nowhere...except to writing this book which I suppose was the start of his successful writing career.

I don't know if someone unfamiliar with the logic of transfinite cardinals would be able to really understand what "Aleph-null" is after reading this book, nor why this infinite number is still too small to describe the how many real numbers there are, but if you already know (or can look it up in a set theory book somewhere) then this psychedelic journey to infinity and back can be a lot of fun.