What's in a name?

Awhile back I wrote a novel that I've been calling Ex Libris from day one. It's an historical fiction/thriller for bibliophiles. It is woven from the histories of various collections of books and the claims these libraries have upon a single book which might reveal the location of yet another older and infinitely more valuable library... which sounds convoluted but isn't.

The point being that "Ex Libris" (Latin for 'From/out of the Library') is the perfect title for such a book.

But there's already an Ex Libris out there. It is a book of an entirely different sort, which is generally sold in a different section of the average bookstore than mine would/will be. Even worse, the fallback title I had in mind, Palimpsest is a novel that is coming out in paperback in February.

I just can't seem to win.

The Writer's Digest Guide to Query Letters expressly forbids pitching a book with a title that's already out there. It pointedly makes fun of someone who does so, as a matter of fact. While I'm not generally disposed toward taking any one guidebook's advice as a mandate from on-high (with all due respect to Ms. Burt-Thomas), I worry that any of the other titles I've come up with will fail to as fully encapsulate the story I have told and "Untitled" leaves a great deal to be desired as well.

I readily admit that this is probably a tempest in an inkwell. The jitters of a first-time novelist are innumerable, but nothing I've come up with and nothing that any of the others I've discussed it with (sorry guys) fully captures the essence of the novel either. Working titles rarely make it all the way to the dustjacket on the store shelf, but I do worry that by any other name it just won't sell the same.