Only one epub file will not open in ADE or on my Nook. The others I downloaded will open on both and will copy to the Nook as usual.

I download epub books from Overdrive. Only one epub file will not open in ADE on my Mac or on my Nook. The many others I've downloaded will open on both and will copy to the Nook as usual. Using the latest edition of ADE. Could be a corrupted ePub file? Curiously, this is the second time I've downloaded this epub from the same site, and I had no problem the first time. It still has 9 days remaining in the borrowing period.