In 2019, Knox published "The Absolute Book", a fantasy novel that won critical acclaim both in New Zealand and overseas. The book attracted particular attention after a January 2020 book review by "Slate" writer Dan Kois headlined "This New Zealand Fantasy Masterpiece Needs to Be Published in America, Like, Now". The book was subsequently acquired by overseas publishers. It was published in the US and Canada in February 2021, and in the UK in March 2021. "Kirkus Reviews" wrote: "This darkly luminous fantasy reads like a mystery, thoroughly and wonderfully transporting readers to another world." "The Times" described the novel as "bursting with imagination" and "a bewitching, frustrating, strange and perverse novel". Nina Allan, reviewing the novel for "The Guardian", said it "has the feel of an instant classic" and "is everything fantasy should be: original, magical, well read". She praised the diverse characters and the book's "genuine feeling of jeopardy".