Ngaio Marsh is recognised as one of the original Queens of Crime: her works sit alongside the greats of the crime fiction genre’s golden age including Agatha Christie, Dorothy L Sayers and Margery Allingham. Dame Edith Ngaio Marsh is just as well known, in her homeland of New Zealand, for her significant contributions to the world of the theatre. This paper explores the impact of a collision of Marsh’s two worlds – the world of the murder mystery and the world of the performing arts – in her series of Roderick Alleyn novels. With particular focus on her first novel set in a theatre, Enter a Murderer (1935), and the last novel penned by Marsh, also set in a theatre, Light Thickens (1982), this paper will look at how realistic Marsh’s portrayal of the performing arts is as well as the relevancy of such details in building a plot for a crime fiction novel.