49. Thrones, Dominations by Dorothy L. Sayers & Jill Paton Walsh

Sayers passed away before completing this mystery novel which takes place in 1936. It was finished by Walsh and published in 1998.  Lord Peter Wimsey and his new bride, the writer Harriet Vane, are adjusting to domestic life together when an acquaintance is found murdered in her suburban home. The historical backdrop includes the death of George V and Hitler's rise to power.