The Dead in Their Vaulted Arches

The main mystery in this the sixth Flavia de Luce book is not the dead bodies, though there are two of those, but something from the past. Also, unlike previous books in this series, Flavia herself is not in danger. She does, however, have deep mysteries to unravel. In this story we get some poignant family scenes, heartbreak, betrayal, and murder. (What's not to like?) Mysterious government agencies become involved and the secret history of the de Luce family is finally revealed (at least some of it).
This is one of the better books in the series. Recommended. But to get the most from the story, you really should start with book one.