Written by Brian Finch. The scripts for the two-part story were commissioned as "Livanthian" on 14 August 1983, and later became "Leviathan". "Leviathan" would have seen the Doctor arriving in what appeared to be medieval times. No official reason has been given for its late cancellation during Season 22, but the most likely explanation is budgetary reasons . "Leviathan" was later adapted by Paul Finch (Brian's son) for Big Finish as a late addition to their "The Lost Stories" series in January 2010, after Paul Finch contacted them about his father's script. Big Finish had not previously known about "Leviathan".