Planet of the Ood
SPOILER Summary: The Doctor and Donna travel to a random time and place in the galaxy and end up in the 42nd Century during the 2nd Great and Bountiful Human Empire. They come upon a dying Ood who briefly has the same red eyes of possession the Doctor had previously 
seen. Bluffing their way into a presentation for potential buyers of Ood, the Doctor and Donna discover that things aren’t going that well for this slave-race, or their human owners. With the Doctor being able to now hear their song of captivity, he decides to try to free the Ood as more and more of them go insane. The Doctor soon learns that the Ood have three brains — one in their skull, one they hold in their hands, and a giant, collective brain. The removal of the held brain is how the humans enslave them and the giant brain is kept in a field to interrupt its telepathic ability. However, in the end, the field around the giant brain is lowered and the Ood are freed, thanks to the Doctor’s efforts.
Thoughts: I had some problems with this episode, namely in the ultimate design of the Ood. Think about it for a moment. They have a brain in their skull, then they carry a mini-brain 
around in their hands, and finally there’s a giant brain. So, assuming the giant brain has some method of protecting itself (which didn’t appear to be the case but for the reasons of discussion, we’ll assume so) and the Ood have to protect their mini-brains by carefully holding them, how do the Ood do ANYTHING without causing their mini-brain serious damage? Seriously, this is one huge design flaw and frankly, the Ood should have gone extinct.
OK, so they can easily survive without the mini-brain, where (how convenient), humans figured out that they could cut off that brain and just install a translator on a tube. Isn’t that lovely?
Of course, we have to get preached to on the evils of slavery. The episode tried to push over the fact that the Doctor wasn’t that concerned over the Ood slavery issue on the previous encounter because he was too occupied dealing with “Satan,” but I suppose they felt that the Doctor needed
to free millions of beings after having to allow 20,000 humans dies in the previous episode. Everything just felt forced, preachy, and I just didn’t care.
The one bit of interest was the Ood telling the Doctor that one day, his song must end. I’m not sure what that implies, but it does seem to throw out a possible regeneration (which I’ve not heard about, but I’ve not been reading up either) or something. I don’t think it means the end of the series even though I’ve read that next year, there will be no series but rather a few TV movies, which is rather a bummer.
The episode reminded me that I’m getting older. I kept thinking I recognized the actor playing 
Klineman Halpen but was surprised when I learned it the character was played by Tim McInnerny, whom I’ve seen countless times in the various Blackadder British comedy series. Also, Roger Griffiths (Everton in the British comedy Chef!) was also in this episode, looking much older as the security head Commander Kess.
Next week: the return of Martha and a classic Doctor Who villain — the Sontarans.