Born and educated in Christchurch, Ngaio Marsh studied art at Canterbury College, revelling in the landscapes of the Southern Alps, but also earned some income from writing articles, poems, and stories. In 1919 a touring Shakespeare company sparked her passion for theatre, especially when she was invited to tour with the group to gain practical experience. For the next decade she painted, wrote, coached drama, and directed plays, managing to support herself without inherited wealth. In 1928 she set off for the first of many extended visits to London, financing her travel by writing articles about her journey. In 1931 she produced the first of many elegantly written detective novels which focused on an urbane sleuth who came to be regarded as comparable with similar characters in the work of contemporary novelists such as Dorothy Sayers. She spent the wartime years in Christchurch, caring for her ageing parents and reviving her interests in art, as well as writing and amateur drama. Her contribution to student drama was especially notable - many aspiring actors gained from her skilled and meticulous tutoring in their craft and became leaders in New Zealand theatre. Her Shakespearean productions for the university won plaudits both nationally and in Australia.

From 1950, each year usually brought a new detective novel, at least one Shakespearean production, and a visit to London. Although her later years brought fame and at least a modest fortune, she remained a loyal friend, a wonderful mentor to young people, and a generous supporter of theatre in her beloved Canterbury.