[1] In 2012, Allan began researching the history of European settlement in New Zealand in order to further understand her own family tree.
[2] In doing so, she came across material regarding a man named John Finnigan, who was apparently murdered in 1865 along with his mother and two brothers.
The incident was referred to as the Otahuhu Murders, and formed the focal point for her novel, Purgatory,[3] which was published in New Zealand in 2014.
In 2018, Allan was appointed Writer-in-Residence at the Michael King Writer's Centre.
In 2019, Allan was appointed Creative New Zealand University of Waikato Writer in Residence in Hamilton for the year.