The Murder on the Links

Stabbed in the back
A pieced of lead piping nearby
It should be a simple case...Poirot is summoned to France, but arrives too late to save his client, whose body now lies face down in a shallow grave on a golf course.
Why is the dead man wearing his son's overcoat? And who was the intended recipient of the love-letter in the pocket?
Before Poirot can answer these questions, the case is turned upside down by the discovery of a second, identically murdered corpse...