This reminds me of a movie where Sean Connery was a monk/investigator. The movie was called "Name of the Rose". It also had Christian Slater in it. In a nutshell, Sean Connery was the character, Brother William of Baskerville, that was sent to a monastery to investigate a strange murder. He discovers that the culprit of the murder was a book whose pages were poisoned (maybe the same type of arsenic?).
Good movie, although I thought the ending was a little dissatisfying, what with the library and all those rare and valuable books going up in flames. Enjoyable to see the Grand Inquisitor get his comeuppance from the local peasanty, though.
Good movie ... much better book. The plot was 'way too complicated to translate properly to screen.
My first thought too. A GREAT book!