Planet of the Ood is the third episode of the fourth series of the revival Doctor Who, starring David Tennant as The Tenth Doctor and Catherine Tate as companion Donna Noble. The episode brings back The Ood, a race last seen in Series 2's The Impossible Planet/The Satan Pit.
The Doctor and Donna find themselves traveling to the future, and to a distant planet, where they encounter a dying Ood. The last time The Doctor had encountered the Ood, they had been under the influence of mind control, and it seems this time, they are also under some type of mind control, although from a different source. It also seems that the Ood are being raised and programmed for a live of slavery by a large corporation, something that brings disgust to both The Doctor and Donna, although they are more busy escaping the imminent violence to do much about the larger moral issues. By the end of the episode, they find out the truth about the Ood, who are lobotomized into slavery, and help free them.
One of my criterion for judging a Doctor Who series is how soon and how often they go to other planets. The Ninth Doctor never left earth in his televised adventures, but this Fourth Series would feature about half of the stories on distant worlds. In some ways, Planet of the Ood is reminiscent of Series Two's New Earth: the Doctor goes to distant planet in the future, and confronts issues of ethics and human exploitation. But for whatever reason, this episode works in a way that one did not.
"Planet of the Ood" is not likely to be anyone's favorite Doctor Who episode. The scenery is spectacular, but stark. The dialog doesn't have any witty lines or famous speeches. And, strangely enough for a Doctor Who episode, The Doctor doesn't really save the situation, being mostly an observer of events. But it is a good episode, and an important one. As I wrote about the the last episode, Series Four is turning to more serious matter, and this episode, a long meditation on oppression and human callousness, is a perfect example of that.