Following the murder of Albert Noel Parke's first wife and the eventual jailing of the perpetrator, Welshman William Jones, the local police in Cornwall begin to suspect Parke himself. A Detective Inspector in the London Metropolitan Police, known as 'Bobby' to his friends, he is accused of framing Jones for arranging the death of his second wife. Jones was convicted, but Detective Sergeant Arnold Baxter of the Devon and Cornwall Constabulary is determined to uncover the truth.