Maigret Versus Mister Cadavre

Maigret travels ex officio to help the brother-in-law of commisionaire who is a friend of his. The brother-in-law is being anonymously accused of the murder of a man who died having been run over by a train just outside his property. At the same time an ex-inspector that Maigret had had dismissed also appears and seems to be following the same clues and talking to the same witnesses.