The Charmed Ones have nothing to do with the September 22 episode of Doctor Who, even with such a title like “The Power Of Three.”
Instead, The BBC offers this description for the episode:
The Doctor and the Ponds puzzle over an unlikely invasion of Earth, as millions of sinister black cubes arrive overnight…
Here’s the trailer for “The Power Of Three” so you can see for yourself, and if you’ve just seen this week’s show, titled “A Town Called Mercy,” come discuss it on the KSiteTV Doctor Who Forum — we’d love to have more people posting!