When we last left the Doctor, he had regenerated into his fourth incarnation after a deadly bout of radiation. He regenerated from the somewhat middle-aged and debonair third Doctor, into a younger man with curlier hair, more prominent teeth…and as usual, he spends the early hours of his recovery somewhat befuddled.
Eventually though, the Doctor settles into his new persona. His sense of humor is a bit more oriented on slapstick and somewhat more cynicism than the charming wit of his predecessor. He also settles on a more bohemian fashion sense, with a hat, long jacket, and a multi-colored scarf.
After solving another UNIT caper involving a giant robot as his ‘first’ adventure, the Doctor and Sarah resume their adventures, with UNIT Doctor Harry Sullivan now invited along for the ride. Their first stop is in the future, where they discover an “Ark” orbiting the Earth, where humans have been hibernating, trying to wait out until solar flares have stopped ravaging the Earth. However, the hibernating humans have been infested by the Wiiryn, a wasp-like parasite/collective not unlike the Alien from the “Alien” films. The trio manage to stop the Wirynn and save the Ark, and as an additional favor, agree to check if the Earth is safe again. Enviormentally it is, but they also run afoul of a Sontaran attempting to conduct experiments on humans. Defeating the Sontaran, The Doctor and his friends beam back to the ark, but however are diverted….
Here, one of the Doctor’s most important adventures begins. He’s once again on Skaro, the devestated home planet of the Daleks. However, this is many years before he ‘first’ landed here. He’s been summoned here by the time lords to the genesis of the Daleks, to try to stop them from being created in the first place, or to somehow make them more peaceful. Arriving near the close of their war, he finds himself a captive of the Kaleds-the precursors of the Daleks-who are still humanlike. However, he discovers that their chief scientist, Davros-is conducting unethical experiments for the preservation of his dying, mutating race-accelerating their evolution until they become green, blobby, octopus like mutants, and then encasing them into “Mark III” Travel machines, and also programming their minds with a message of hate and death. Although initially believed to be benign, Davros-who with his own ravaged appearence is somewhat the prototype of his creations-is creating the first Daleks.
Trying to gain the trust of both the Kaleds and their rivals the Thals to stop the creation of the machines, the Doctor almost gains the oppurtunity-but then hesistates as he ponders the morality of what he’s about to do. Does he have the right to eliminate them, altering history the way he could be? Does it make him better than them, or on equal terms? The Doctor is mostly unable to resolve this completely, and only is able to delay the Daleks for a bit on the cosmic scale of things. Davros, in the meantime, is betrayed and exterminated by his own creations who see him as inferior. Or is he?
After this epic adventure, the Doctor returns to the Ark, although at an earlier point in time when it was a simple relay station in the solar system. As if dealing with one old enemy wasn’t enough, the Doctor soon finds himself once again against the Cybermen, who this time want to destroy a rogue planet in the solar system-Volga, the “Planet of gold”, as the Cybermen have developed a weakness to the metal. The Doctor is able to defeat them, and he, Sarry and Harry are summoned back to present-day Earth.