Whilst observing a dying planet at the edge of Mutter's Spiral in the TARDIS, the Zircon caused it to explode. Joan believed that the Doctor had accidentally taken them to the time the planet went nova, but the Doctor stated that it was impossible and calculated that the galactic cyclone resulting from the nova would read the Earth as a poison cloud.
After several days, Joan and the Doctor arrived on Earth where they informed General Maxwell-Lennon of the situation. The three visited the Prime Minister at 10 Downing Street where the rescue of a chosen few was planned. Joan was upset at how many people were going to die, telling the Doctor that she wished to die with the rest of humanity. The two drove Bessie to a giant electronic eye where they spotted the Zirconian fleet, who Joan remarked would have to be quite intelligent to do what they had.
The Doctor planned to use the Earth's satellites to create a shield of static electricity to protect the planet from the cloud, but Joan was sceptical that he could generate enough power. They waited until the fleet was within range before activating the shield, causing the cloud to explode and the fleet to be destroyed. The two later visited General Maxwell-Lennon before driving away in Bessie.
Behind the scenes Edit
Joan Brown's sole appearance is in the Mighty Midget Doctor Who Comic reprint of Doomcloud, in which she replaced Sarah Jane Smith, while the Third Doctor was replaced by the Fourth Doctor. As TV Comic's depiction of Sarah was so unlike that of Elisabeth Sladen, no alteration to the artwork was necessary in this case. However, the Doctor does still refer to "Joan" as "Sarah" in one panel that was presumably overlooked in the updating process.