Blood of the Oak by Eliot Pattison, I didn’t know this was the 4th book in a series. If after this small review, if it interest you, it would be a good idea to read the previous three books.
Duncan Mccallum is Scottish man who now has a daunting task in solving the mystery of who stole a native American artifact and killed a young boy who was trying to stop the thieves. At the same time Duncan is puzzled by the murder of a Oneida and almost claim the life of a dear friend capt. Patrick Woolford. Duncan goes out on his own, using his medical training for speaking with the dead to find the murders. During his quest to find the murder and seeking answers, he runs into men who are killing messengers from several different communities. These messengers working in secret and are led by Benjamin Franklin. All leading up to the American Revolution.