The term 'Marsh of Mystery' is associated with the mystery writer Ngaio Marsh (5 letters). Marsh was a New Zealand-born author who wrote 32 detective novels and several plays. She was known for her witty and complex plots, as well as her use of the English language. Her works often featured Inspector Roderick Alleyn, a Scotland Yard detective. Marsh was made a Dame Commander of the Order of the British Empire in 1966 for her services to literature.