I had this problem with an ADE epub that I could only read on my desktop computer. I got a plug-in DRM breaker from somebody whose name I think was Alf, with instructions, and with that I was able to open the book in Calibre and convert it to a mobi for sideloading onto my Fire tablet. Probably you can do the same with the Nook (presumably DRM'ed) epub. In your case, saving it merely as a generic epub.
Here it is:
Moderator Notice
Link removed