The Corpse in the Crimson Slippers

This is a mystery novel that revolves around Philip Tolefree, an insurance broker. Ronald Hudson, a travel writer disguises himself and pays a visit to Philip Tolefree. Ronald presents Philip with an anonymous letter written in code that he hopes the insurance broker can decipher. But Tolefree is concerned and fears Ronald has committed a crime. Then a chance phone call connects Hudson's visit to the murder of a scientist at a country house party. Will Tolefree's worst fears be confirmed? Why did Hudson disguise himself?