Atmospheric Excitation is the phrase used by The Doctor when he made it snow at the end of The Runaway Bride at Christmas, 2006. The reason for that title becomes clear later, but first a large part of the opening deals with the question of Stella’s parentage. I had no intention of going down the same road as Buffy, when her sister discovers she was ‘created’ as the vessel of the ‘light’ and all the hysteria that came with that. The Doctor chooses to lie to Stella, but for her own peace of mind. His evidence is flawed, of course. Stella and Wyn’s DNA would be similar but not identical if they were ‘real’ sisters. Stella’s questions about whether, in some way, The Doctor might be her father, are obvious ones. As Wyn says later, in a curious way she and The Doctor ARE Stella’s parents, but not in the way she imagines.

And so to the planet they visit. And purple is the new black. Purple is the new everything. Acconia is the home of a race of short, purple people. But not Umpa Lumpas. I decided to make those rustic looking houses modern inside. There is no good reason not to. This is a planet with intergalactic communication, so just because the people are small is not reason that their lives should be.

But the Acconians are in trouble, and it’s The Doctor to the rescue, sorting out some old enemies. The Mentors, were a strangely named enemy from the Sixth Doctor era. Mentor is usually a word that means teacher, but the only teaching these creatures did was how to oppress and destroy lives. Here, The Doctor reflects that there are ugly races in the universe who are nice people, but the Mentors aren’t one of them. These are sheer evil.

And they’re at it again here. They are, of course, the slug people that Wyn and Stella didn’t enjoy. And The Doctor doesn’t want to get near them, either. He uses the TARDIS to sort them out and never has to get up close and personal.