The climax of the fantastic, epic 12 part series is well worth waiting for, it's an utterly huge episode, up until this point I'd say it's the darkest of episodes, it signified a real change in direction for the show. The scenes of Sara ageing and turning to dust must have been quite shocking at the time, it was certainly a brave decision to kill off a second would be companion.
There are too many stand out moments to pick out one, but highlights include the Daleks informing Chen the the alliance has ended, Sarah's demise, and of course the big climax.
The music is utterly brilliant, it's such a dark and atmospheric episode, the music adds massively to it.
The level of acting, based on the audio alone is sensational, Hartnell is absolutely fantastic, if it did exist it would be interesting to see just how good he was, he really is the heroic figure here.
Not only is it the best single episode that doesn't exist, but it must also rank as one of the show's best episodes. The serial started off great, dipped a bit in the middle and ended in epic fashion.
I'll end with these words, find it and I'll become the happiest man on this planet.
10/10.