Misplaced

I have a problem — a book my son borrowed from the library has somehow disappeared. I've looked up and down the house, and all through his room, but the problem is that my son has (and I say this without a trace of hyperbole) approximately 35,000 books of all shapes and sizes. Like his parents, he loves to read (and to be read to).

The book is due to be returned tomorrow — assuming I can find it.