The book (not freely available AFAIK): http://www.info.ucl.ac.be/~pvr/book.html

Paradigms map: http://www.info.ucl.ac.be/~pvr/paradigms.html

"Read CTM" may be good advice in general, but at ~900 pages probably isn't the type of answer they're looking for.

There's a draft of the book on one of the author's websites: http://www.sics.se/~seif/DatalogiII/Book/datalogiII.pdf

I'm pretty sure there's a newer still (and legitimate) pdf of the book out there if you're good with the google. The book itself is absolutely worth buying but the pdf might give you an idea of what you're getting.

Peter Van Roy is giving a class in a month or two on one of the MOOC platforms which looks like it will be a pretty gentle intro to the material. I don't know which paradigms he's going to be covering - he's not going to go through the entire book.