And #TIL from the site that ... Emacs has an ePUB mode. But of course.
davdunc: have you tried Emacs' nov.el mode for reading epubs? darn, didn't know it existed
> However, because it is an open format, you can use the excellent nov.el mode and read Mastering Emacs from inside Emacs!
For people who care about, support, or build Free, Libre, and Open Source Software (FLOSS).