Steel Witches Tom Fletcher Series, Book 2.

Tim Fletcher has left the police force, and its cold outside. Working as a P.I. in Cambridge, he is dragged back into his own troubled family history by an enigmatic message from his missing father. Tom's intrigue begins to spiral into ever darker conspiracies. How is an American company involved in an officially-suppressed story from World War II? Where is the US Air Force base that seems to be the key to centuries-old mystery? And who were the...