Threats at Three is a series book by Ann Purser. This is actually the tenth book in the series. All are centered around the English village of Long Farnden and the lives of characters introduced in the first book which was Murder on Monday.
When I started reading Threats at Three I didn't think I would like it but hung in there for a chapter or two and began to get interested, not so much in the plot, but in the characters. Actually, the plot was a little thin. For instance who was trying to burn down the hall? If that was clearly established I missed it. The characters, however, seemed well defined and tempted you to read the forerunner books to see how they developed.
If you like fast moving action, dead on suspense, and a stunning rap up, this book is probably not for you. If, instead, you want to spend a leisurely couple of days in an English village peering in the windows of some of the families then Threats at Three will be your 'cup of tea'.