As we have seen, in Doctor Who’s third broadcast story, ’The Edge of Destruction’ Hartnell’s Doctor, proud and arrogant, who began as a quasi-antagonist in ‘An Unearthly Child’, becomes an ally of and friend to Ian and Barbara, the teachers he had kidnapped. It’s probably his first step towards becoming the protagonist of the show, something we now see with hindsight as being inevitable but which actually evolved organically in these early episodes.
The travellers then journey with Marco Polo, visit the alien world of Marinus, and travel back to the civilisation of the Aztecs before their adventure with the Sensorites. In this story we see how different the Doctor’s role has become.
The story begins with the characters reminiscing about their time in the Tardis so far: ‘It all started out as a mild curiosity in a junk yard’ they say, and later we get a rare glimpse of the home planet of the Doctor (with a burnt orange sky and silver leaved trees) not mentioned again for many years. This outward re-orientation serves to signal the more subtle adjustments that are occurring within the troupe: rather than kidnapper and prisoners, the Tardis crew are clearly now all friends and the Doctor is no longer a captor or under a shadow of suspicion.
The Tardis travellers land on a moving spaceship and at first believe that the crew are dead. One of the crew members regains consciousness however; Ian fully revives him and another woman, and they explain that they are on an exploration mission from Earth and are orbiting Sense-Sphere, the inhabitants of which, the Sensorites, refuse to allow them to leave orbit. The Doctor manages to avoid a collision course set by the Sensorites. Susan displays telepathic ability: she mentally hears the many voices of the Sensorites while the Doctor works out that the Sensorites attacked the human craft because they feared the mineral exploitation of their planet after a previous Earth expedition had exploited Sense-Sphere for its wealth.
The Sensorites are divided: part of their Council plot to kill the newcomers on arrival, but others believe that the humans can help with the disease that is currently killing many Sensorites. Ian then catches this disease and is told that he will soon die. The key point here is that the Doctor works to save Ian’s life unequivocally, finding a poisoned aqueduct working with the Sensorite scientists to cure Ian.
The Sensorites are mistrustful of humans rather than hostile or possessed of world-conquering ambitions. Though they can hold people captive, freeze them and drive them insane, they are not the usual alien threat common to science fiction. But the story is padded out and has much to do with the internal bickering amongst the Sensorite factions. The interesting thing is seeing the Doctor’s persona change from that of potential villain, the kidnapper of his companions in ‘An Unearthly Child’ and the saboteur of the Tardis in ‘The Daleks’ to that of a diplomatic mediator.