The Murder on the Links

The little grey cells, my friend, the little grey cells! They told me.Master detective Hercule Poirot is summoned to Northern France by Paul Renauld, but upon arriving at Renauld's home, the police inform Poirot that Renauld had been stabbed in the back with a letter opener and his body had been found in a freshly dug grave next to a golf course. Renauld's wife claims masked men tied her up and then took her husband away from her, and until then, she had not known her husband had been murdered. A mystery that is seemingly unsolvable, but nothing ever escapes Papa Poirot.