Doctor Who: The Edge Of Destruction (1964)

In its own way, the third Doctor Who story - The Edge Of Destruction - is as historically important to the show as the first two (An Unearthly Child and The Daleks).

Squeezed in after The Daleks to fulfill an initial 13-episode run that the show was granted by the BBC during the production of its first story (after others were dropped and stories were moved around in the schedule), this 47-minute two-parter not only proved the viability of telling stories in this comparatively short period of time (decades before Russell T Davies took Joss Whedon's Buffy The Vampire Slayer model as his template for new Who) but also established a precedent for the money-saving, low budget stories that, again, would become a staple of the 21st Century iteration of the show - with its annual 'Doctor-lite' episode.

What The Edge Of Destruction also did was establish The TARDIS as a character in its own right.

Having left Skaro at the end of The Daleks, The First Doctor, Susan, Ian and Barbara are rendered unconscious by a sudden explosion within The TARDIS control room, but once they start to wake up confusion and paranoia reigns; the doors open and close on their own; strange images flash on the monitors; ship systems don't work properly.

The Doctor, having suffered a cut to the head, blames Ian and Barbara for their misfortune; Ian doesn't appear to know where he is and Susan goes a bit loopy, threatening people with a pair of surgical scissors. Only Barbara seems to keep a clear head.

None of them can figure out what has happened: has the TARDIS crashlanded or hit something? Has an alien intelligence gained access to the ship?

Accusations and recriminations fly, harsh words are exchanged as The Doctor tries to logically deduce what is going on while Barbara relies on her intuition.

The Edge Of Destruction, penned by story editor David Whitaker, is primarily concerned with developing the personalities of the four main characters and, eventually, building a degree of trust between The Doctor and his two new human associates.

Some of the effects - in particular the melting clocks - probably worked better on paper than in reality, and ultimately a degree of surreality is suggested that the story doesn't merit, but the claustrophobic nature of the piece and the character growth more than makes up for the thinness of plot and the obvious cheapness of some of the props (note the handwritten 'fast return' notice on the ship's console).

I believe this remains to date the only televised story to take place entirely within the confines of The TARDIS, a gimmick that is crying out to be revisited, especially now the vast expanse of the craft's interior has been established in subsequent stories.