See capital S?

I have a book online, I want to save offline.
In the main page, there's an index which has a TOC, with each entry in the TOC linking (hyperlink) to a chapter.

I basically want to download the page, with all it's sub pages offline, for offline viewing, without needing to download each page separately.

In years past, there were many programs that could do that, and would even nest links within the pages (correct HTML links to local files).
It surprises me that there's no (free) extension for Google Chrome, and neither Opera?