Mildew on the cover of a book

[Jean in Newcastle]

I have a similar problem to the other mildew problem posted on the board right now. I just received a used book I'd ordered yesterday - complete with a white mildewy stain on the cover (it is hardback). Should I return the book? (We are really overdue for reading this because if I return it, it will be the second time I've ordered this book and had to return it. My library doesn't have it.) Can I remove the mildew stain? My husband suggested spraying it with a bleach mixture. Should I try it? If I ruin the book, then of course I couldn't return it. . .