A Necessary End by Peter Robinson is the third book in the Detective Chief Inspector Alan Banks mystery series. It's a fine mystery and is unusual for its carefully braided plot. As Banks says, "Oh for a nice English village murder, just like the ones in books: a closed group of five or six suspects, a dodgy will, and no hurry to solve the puzzle."
Instead he gets the murder of a policeman during a demonstration against nuclear power that got out of hand and as a result has some hundred or so suspects. He also has no weapon and no apparent motive, but what he does have is an old nemesis sent from Scotland Yard to lead the investigation, Dirty Dick Burgess, an unprincipled detective he worked with in London years ago. Burgess is still ambitious and obnoxious, alienating the witnesses with whom Banks has worked to build rapport. Burgess is also in a hurry, more interested in closing the case quickly than in identifying the person who actually killed the policeman.
It doesn't surprise anyone that Police Constable Eric Gill got a knife in the ribs during the fracas. He is noted for volunteering for special duty controlling crowds, and he is also known to be quick with his baton. But who would hate him enough to actually kill him? Perhaps it was some sort of accident?
The investigation begins to focus on the people who live at Maggie's Farm (named after the Bob Dylan song), two ageing hippies, the artist and Tarot reader who rent apartments in their barn, and a young man whom they found on the street and took in. All are counter-culture types and four of them were at the demonstration.
Chief Inspector Banks loves opera, as we learned in an earlier book. In this book we fine he also enjoys and knows a lot about American jazz. The songs he listen to provide background music for the story. A discography would have been useful.