Sup with the Devil by Barbara Hamilton

In this mystery Abigail Adams gets drawn into mysterious circumstances at Harvard which center around a document whose contents are hidden by the Arabic script used to write it, a collection of books owned by a pirate that may have fallen into the wrong hands, and that pirate's hidden treasure. It seemed to take a while for this mystery to really get going, but it all came together nicely in the end. Hamilton continues to write excellent historical fiction.