The Invasion is amazing. It's the immediate follow-up to The Mind Robber (which makes me glad I saw that one first, as the initial sequence would have left me confused otherwise) and since episodes 1 and 4 were deleted by the BBC (grr...) they replaced those two eps with gorgeous black-and-white animation using the audio tracks that were recorded by fans when the originals first aired. The only downside is that the animators forgot that Zoe was supposed to be wear the sparkly catsuit from The Mind Robber during episode 1, so in the animation she appears throughout it wearing the dress she's only supposed to put on later on. Ah well, that's but a little snag. I'm doing a recap, by the way, which I'll be posting on my LJ (episodes 1 and 2 are up already) but I think you should watch it instead.