Mr Mottram is found dead in a locked room with a gun shot wound to the face and a fatal knife wound to his heart.
Miles Bredon & his wife investigate.
Knox is very funny and exceptionally literate, I'd wager that Hammet modeled "The Thin Man "on these two. Both couples wise cracking while solving the mystery . It appears Knox got there first with this published in 1927 , the The Thin Man published in 1934.
Good fun