His works include Snatch! (1969), Once A Spy (1981), and a series of murder mysteries set in England between 1921 and 1949 featuring Detective Inspector John Madden of Scotland Yard (later retired). The first of these, River of Darkness (1999), won the Grand Prix de Littérature Policière for best international crime novel in 2000 and was nominated for Edgar, Anthony, and Macavity awards in the States. Airth found inspiration for that tale in a scrapbook about his uncle, a soldier killed in World War I. A sequel, The Blood-Dimmed Tide, was published in 2003, and a third book, The Dead of Winter, in 2009. Although Airth initially intended to write a trilogy about Madden, in 2014 he produced a fourth entry in the series, The Reckoning, and followed that with The Death of Kings (2017).