Planet (Follow the Phantoms)

An Earth-like planet with a purple sky was home to a humanoid species and the slug-like Scythias. Victoria Waterfield nicknamed it "Cloud Seven" as that was her lucky number.

When the Second Doctor, Jamie and Victoria visited the planet, they saw on the TARDIS scanner a humanoid army marching through a desert. When the Doctor saw what appeared to be a low-lying cloud, which he knew to be impossible in the planet's atmosphere, he decided to investigate it. At Jamie's urging, he tried to make contact with the army, only to find that they could not see or hear him, and passed through him as if they were ghosts. After the army entered the cloud, the Doctor deduced that it was actually an echo across time, and that the people were from the distant past. Jamie entered the cloud to get a look at the city which he appeared inside it, where he found by the army and hailed by their leader Ziita as the one prophecied to lead them in battle against the Scythias. Jamie instead fled into the desert, where he nearly became caught in the crossfire of the battle with the Scythias, but escaped into the cloud when it appeared before him and reunited with the Doctor. (PROSE: Follow the Phantoms)