I don't ensure because I can't ensure but the book will sell much more than 1 BTC. The lender won't lose a satoshi. On the contrary, he will make 3 times more.
And how can you guarantee that? If you are so sure I don't see why you can't pony up some collateral. Not to mention what happens if you book earns squat - how are you going to be able to pay back the loan if at all?