Dorothy Leigh Sayers 
Whose Body? 

The stark naked body was lying in the tub. Not unusual for a proper bath, but highly irregular for murder — especially with a pair of gold pince-nez deliberately perched before the sightless eyes. What’s more, the face appeared to have been shaved after death. The police assumed that the victim was a prominent financier, but Lord Peter Wimsey, who dabbled in mystery detection as a hobby, knew better. In this, his first murder case, Lord Peter untangles the ghastly mystery of the corpse in the bath. (Goodreads)