As a plot point in my project -- kind of a big one -- I need to have the main character lose a rare and old (and magical) book by having it accidentally returned to the library by a well-meaning but rather unobservant side-character. The book isn't marked to be a library holding, but it's written in a completely unintelligible language to everyone but the MC. It's magically preserved but is bound and written in a foreign and quite old style.
What I need to have happen is for the library to refuse to return the book to her when she goes to ask about it. There can be suspicion of foul play or illegal acquisition of the book or anything else, but I need to know if there would be any possible reason for this to happen. The reason for this plot point is that as the MC reads the book, she starts having hallucinations and the only way to get them to stop is to finish reading the book, or so she hopes, and so losing the book makes life very difficult for her. She'll get it back eventually by breaking in (small town library, very little security) due to the fact that her hallucinations are driving her crazy, but I just need an initial reason they'd tell her no.
Setting is modern day US of A, but the state is really up in the air, so if a specific state has special laws regarding this, then the setting can be moved there. I'd prefer southwestern, since that's the region I'm most familiar with, but anything is fine. Suggested Google searches are also awesome, because putting in "library refusing to return a book" and the like only gives me stories about people refusing to return controversial books to libraries, which, while amusing, isn't quite what I'm going for. ^^'
 Thank you all so much! I think I definitely have an idea of how this is going to go down now! (wow I love this community! ♥)