The Piccadilly Murder

The Piccadilly Murder is a 1929 mystery detective novel by the British writer Anthony Berkeley.
Ambrose Chitterwick is a witness to the death of a lady in the lounge at the Piccadilly Palace Hotel, shortly after her companion dropped something into her coffee. Chief Inspector Moresby is convinced she was murdered by him her nephew and sole heir, Major Sinclair, using prussic acid. He arrests Sinclair and plans to use Chitterwick as starwitness for the prosecution. However, nagging doubts in Chitterwick's mind lead him to turn amateur detective and find the real truth.