What is the author's style in Whose Body?: A Lord Peter Wimsey Novel by Dorothy L. Sayers?

The story is written in a mysterious way so that the reader is constantly left guessing. For example, the reader hears Peter's thought process that leads him to know the identity of the killer and he immediately reads the Who's Who entry for Sir Julian Freke, which makes the reader understand that Freke is the person Peter believes guilty of one or both of the crimes, but the reader is left to decipher the clues as to why Peter believes this to be true.