Season Twenty-Three of Doctor Who was a product of the most turbulent period in the original television series' history.

The previous season had seen Doctor Who criticised for the level of violence shown, not least from high up in the BBC itself. With plans already laid for Season Twenty-Three, and scripts already being written, it was therefore something of a surprise when the plug was temporarily pulled on the show. Newspaper headlines proclaiming that the show had been axed were soon in evidence, but the BBC were swift to maintain that the show would be back the following year, albeit six months later than usual in a new Autumn timeslot, and would actually have an increased number of episodes — words that any politician would have been proud of, as the reality was that the series would be changing from thirteen 45-minute episodes to 14 25-minute episodes...

As part of this change, the existing scripts for Season Twenty Three were scrapped, and a new set were commissioned. Three of the abandoned scripts were eventually novelised by Target Books in the late-1980s. The Nightmare Fair and The Ultimate Evil were published in 1989, with Philip Martin's Mission to Magnus appearing in 1990.

Aware that the series itself was now effectively on trial, producer John Nathan-Turner decided that the season should see the Doctor himself put on trial by the Time Lords, and came up with the idea of a story arc which spanned all fourteen episodes, with four distinct sections showing various adventures as part of the evidence presented. Although these were numbered Parts One to Fourteen on screen, the novelisations from Target Books treated them as four distinct stories, each being novelised under a different title. For the purposes of this page, the book titles will be used to distinguish each section.

With the basic format for the season established, things then went from bad to worse. Robert Holmes had been commissioned to write the opening four-part story story as well as the two-part conclusion, but ill-health meant that he had only finished the first half of The Ultimate Foe before he died. Eric Saward, who had recently departed as script editor on the programme, then took over resposibility for writing the concluding episode, but his working relationship with producer John Nathan-Turner then broke down irretrievably and Saward withdrew his script. At which point Pip and Jane Baker, who had written Terror of the Vervoids, were hastily asked to finish off the season.