Is Bookselling A Dangerous Business?

A colleague sent me a link to a blog called A Secret Fire, at secretfire.wordpress.com, which is written by a chap called Martin Langfield to publicise his second novel, of that name.
Part of the plot concerns a book auction at Sotheby's in 1936, which really happened, though the rest of the novel is fictional (I hope!). A representative of Francis Edwards booksellers bought a manuscript written by Newton for the princely sum of nineteen pounds and ten shillings - and no-one knows where it is now.
This is especially interesting to me, because the antiquarian section of Hay Cinema Bookshop is Francis Edwards, and they were certainly around in 1936!
In the book, the hapless bookseller is hunted down by Nazis, and killed - but could that elusive manuscript still be lurking amongst the antiquarian treasures? Or did the Nazis get it?
Maybe I'd better be a bit wary of any customers coming in with dodgy German accents!