Nick Willard, who acts as the Doctor's companion in this story alone, was the first person of colour to do so, in any medium. Sharon Davies would later become the first recurring POC companion, after being introduced in 1980's Doctor Who and the Star Beast.
The Doctor arrives in London to find that Earth's people have been hypnotised into repeating the actions they did the day before. Can the Doctor free them from their conditioning in time to stop an invasion by the Zerons?
- The Doctor and Nick go to the Post Office Tower.
- The third panel of Zeron Invasion (which depicts an exterior view of the Doctor's cottage) was recreated in the 2015 comic The Pictures of Josephine Day.