Andrew Beeken originally pitched the idea to Jonny Orme as a Dark Comedy. When Jonny wrote the script he made it into a thriller, wanting the humor to be conveyed through the performances. The comedic side of the script was soon abandoned during filming when Cromwell and Bridger improvised the dialogue in their final conversation.
Jonny Orme asked Dan Hawbrook to rewrite a section of the film between shooting days to make the tone in the second half darker when he found himself struggling with what to change.