Margery Allingham 
Pearls Before Swine 

Campion returns from three years’ work for the War Office in Europe to find that Lugg, his manservant, has brought him an unusual gift: the black silk nightdress-clad body of a dead woman, an apparent suicide. Wanting only to get away to a well-deserved rest, Campion must instead assist Detective Chief Inspector Oates and Superintendent Yeo in unravelling a tangled plot of deception and murder as the war draws to its conclusion.