"Yellow Fever and How to Cure It" was a three-part story by Robert Holmes that was scheduled to be recorded third and transmitted fourth in the original Season 23. It would have taken place in Singapore and featured the Autons as the monsters, with either or both of the Rani and the Master appearing, Brigadier Lethbridge-Stewart would have also returned. The first episode was commissioned on 26 October 1984, before being put on hold. The entire story was subsequently commissioned on 6 February 1985, Nathan-Turner hoped to have Graeme Harper direct the adventure. After the news of the hiatus, Holmes was asked by the production team to continue with the story but as six 25-minute episodes, this version seeing the removal of the Master from the plot. Holmes reportedly only completed a story outline before the planned Season 23 was completely cancelled.