Nowadays we are so used to the 45 minute story format and whilst this story is two 25 minute episodes that together make this running time technically this is Doctor Who's first attempt to tell a narrative in such a short amount of time.

Is it successful?

Well, it partly is and it partly isn't.

The Edge of Destruction sees the TARDIS trying to warn the crew about some impending disaster through various oddities like melting clock hands and influencing the Doctor (William Hartnell), Susan (Carole Anne Ford), Ian (William Russell) and Barbara's (Jaqueline Hill) behaviour.

This is an enjoyable enough story to watch and one that's suitably simplistic for a classic series two-parter. It creates a sense of paranoia well and doesn't feel like filler. It's a shame then that the resolution is such a let down.

Spoilers follow.

Because you see, when it's revealed what the TARDIS was trying to warn the crew about...it turns out it was just that the fast return switch was stuck.

Seriously.

The entire events of the two-parter were all because of one switch.

And that's not the only weird decision because earlier Susan tries to threaten Ian and Barbara with the deadliest item she can find..a pair of scissors. It's a scene that's nothing short of daft and really should have been replaced with something else.

Having said that, there are plenty of good moments. The Doctor's monologue is great and it's nice to see a story set entirely on the TARDIS. The cast all give great performances too. It's just a shame that in conclusion the story is let down by poor decisions by the writer David Whitaker.