After family of blood, which was frankly excellent, this episode was, in my eyes, truly superb on so many points. It was so good in fact, that I finally signed up to IMDb after having trusted the user's opinions for a few years now, just to give it 10/10 and a smashing review! The story was just perfect, the effects were relatively simple but yet highly effective (exactly how it should be!), and the acting was spot on. This must have been the best episode I've seen probably since the beginning of the next-gen Doctor Who 2 years ago. Don't get me wrong, episodes such as Doomsday in series 2 were really excellent, but this episode really brought back the old Doctor Who feal in terms of sheer simplicity with maximum effect. I'm old enough (in my mid 20's in fact) not to have had nightmares in many years, but after this episode, I came close, having had my first bad dream since I can remember!! Really worth watching; The DVD of the whole series should be out in the autumn I guess, and i'll be buying it just to see this episode again!