Dame Ngaio Marsh wrote her first whodunnit in 1931, and introduced the world to suave, reliable Detective Inspector Roderick Alleyn. She soon became a bestselling author — even more popular than Agatha Christie. In this documentary about the Christchurch-born author, actor Peter Elliott (Shortland Street) dons Inspector Alleyn's black hat and leather gloves to meet Marsh's extended family, former protégés and biographers, and explore the "mysteries" surrounding the anglophile's personal life. Author John Curran discusses Marsh's deep love of theatre and her reputation as a "reassuring read".