By Hook or by Crook — Emma Lathen

A rivalry sealed in blood triggers a subtle and deadly revenge plot that links a powerful business and a vast estate to a double murder...

John Putnam Thatcher is faced with two murders -- the result of a bitter family feud. John Putnam Thatcher knows who the murderer is -- but has no proof. John Putnam Thatcher remembers the words of a man about to be murdered. John Putnam Thatcher is dangerously close on the tracks of the murderer.