In 1983, when Knox was 24, she started a degree in English Literature at Victoria University of Wellington. A year later, she started work on "After Z-Hour" in Bill Manhire's Original Composition course at Victoria. The novel is about the ghost of a World War I soldier, and it was inspired by a childhood memory; at age eleven Knox fell from a walnut tree on Anzac Day, and while in the hospital she overheard a conversation between an older man and her father about Passchendaele and life on the Salient in 1917. Bill Manhire encouraged her to write her novel, and told her he would be more interested in seeing her complete it, than her degree. "After Z-Hour" was published in 1987 by Victoria University Press, and Knox graduated from Victoria University of Wellington the same year. She was also awarded the ICI Young Writers Bursary award that year.