Axista Four

 was a largely uninhabited planet colonised by the Tyrenians, genetically-modified human supersoldiers, circa 2434. In that year, it was also chosen by Stewart Ransom an as ideal planet to establish an Independent Earth Colony, on the mistaken assumption that there was no other life there. The colonisation was part of the Back to Basics movement, which argued that humans had grown too reliant on technology by the 20th century. 5,000 human colonists travelled to the planet in The Big Bang. However, on Planet Fall Day, as part of a conspiracy involving the Tyrenians, the ship crashed on arrival after it was shot down by Tyrenian defence satellites, killing many of the colonists, including Ransom, and leaving others, like his daughter Kirann, trapped in suspended animation without the medical experts to safely release them. Battledroids Ransom had intended to dispose of on landing attacked the Tyrenian settlement and sent the survivors into hiding. The surviving human colonists built a settlement, Plymouth Hope City, modelled on those of the Old American West.

In the early 26th century, Tam Kartryte was elected Acting Leader of the Colony. He resisted calls from the Realists to go against the principles of the Back to Basics movement on which the colony was built, while the Realists argued that the colony was slowly dying. In practise, the Back to Basics intentions had been taken to the extremes; the Ransoms' intention was to build a settlement less reliant on technology but not one completely devoid of it.

Despite the colony's independent status, in 2534, Earth forces intended to resettle 80,000 refugees who had been displaced by the wars with the Daleks, which the underdeveloped colony could scarcely accommodate. The Second Doctor, Jamie McCrimmon, and Zoe Heriot visited this colony during the crisis and discovered the Tyrenians had claimed the planet first. The Doctor revived Kirann Ransom from suspended animation and she became the new leader of the colony, uniting Loyalists and Realists behind her.

War between the humans and Tyrenians threatened the colony when the hibernating Tyrenians began to revive but the Doctor negotiated a peace settlement. They also foiled a plot to reactivate the battledroids and wipe out the colony outright, allowing the incoming refugees to start afresh. After the crisis, Earth forces agreed that, after the arrival of the refugees, the human and Tyrenian colony would be left in peace.

The Seventh Doctor told Ace that, according to legend, Ransom's colony "had a long and happy existence; a really successful venture." Millions of years later, in the far future, Axista Four went nova, becoming a fireball. (PROSE: The Colony of Lies)