My cold has devolved into a mild sniffle, the universal cure for which is to sit quietly in the sun and read something comforting and familiar. For me that usually means either Harry Potter or Agatha Christie. On this occasion, I chose the latter. TMF isn’t canon; it doesn’t have one of those marvelously ingenious solutions that imprint instantly and for all time on the memory. The plot involves a series of anonymous letters delivered to the occupants of a small English town, which coincide with some unnatural deaths – are they connected, and if so, how? It’s also not conventionally structured for a Christie, in that Miss Marple doesn’t appear to solve things until close to the end. But like almost everything she wrote, it’s deeply satisfying, and, even if you already know the solution, it’s fun to recognise the clues as she slips them in one at a time.