The Doctor, Sarah Jane and Harry are intercepted by the Time Lords. They want the Doctor to interfere with the creation of the Daleks, who are on their way to conquering the Universe. They give him a Time-Ring, which will return them all to the TARDIS. They are transported to the planet Skaro. The thousand-year war between the Thals and the Kalends has ruined the planet, and each side is hiding in its dome to continue the war, sending out soldiers into a landscape of shell-bombardment and gas-attacks.
They take shelter from chemical weapons. Sarah is separated and meets the Mutos—mutated exiles from both sides. With them, she is captured by the Thals and forced to load radioactive material in a missile. The Doctor and Harry are captured by Kaleds (The Time-Ring is confiscated) and taken to a Kaled bunker, where they meet Davros (Michael Wisher). He is blind, but his ruined eyes are replaced by a single electronic blue eye in his forehead, and his crippled lower body is encased in the bottom half of a Dalek shell. He is showing off his Mark III Travel Machine in which the Kaleds will be encased to move around in the future when they have all mutated into Daleks. One of Davros’ scientists, Ronson (James Garbutt), confesses to the Doctor that he knows Davros’ experiments are unethical, and the Doctor persuades him to put a stop to them. Davros simply turns to their enemy, the Thals, gives them a formula to weaken the Kaled dome, and goes back to making Daleks.
The Doctor and Harry escape to the Thal dome, and rescue Sarah and the imprisoned Mutos. But the Doctor is captured by the Thals and is forced to watch the missile attack. Except for those in the Kaled Bunker, everyone in the Kaled Dome is killed. Davros then blames everything on Ronson and kills him and convinces the remaining leaders to let his Daleks attack the Thal dome. A few, like the Doctor and his companions, escape to the Kaled Bunker. The Doctor shows the Thals and Mutos how to destroy the bunker, where the time-travellers search for the Time-Ring. Davros captures the Doctor and forces him to reveal what he knows about the Daleks’ future weaknesses, so he can program them to be invincible.
Other scientists working for Davros free the Doctor, and he rigs the Dalek incubation room with explosives. As he is about to set off the explosion, he hesitates, wondering if he has the right to wipe out an entire intelligent species. To his relief, Davros agrees to stop the experiments and allow the Kaled leaders to vote on the dark project. The Doctor recovers the Time-Ring and destroys his recording of the Daleks’ future. Of course, this was all a trick, giving the Daleks time to destroy everything. Harry and Sarah escape, while the Doctor tries to set off the explosion, but a Dalek accidentally sets it off. The Doctor escapes, but Davros and the Daleks are trapped inside. The Daleks refuse to follow Davros’ orders anymore. He appears to be killed by his own creations. The Doctor believes he has set back Dalek evolution by centuries. He and the companions use the Time-Ring to return to the TARDIS.
John Franklyn-Robbins, who played the Time Lord who set all this in motion, was supposed to resemble Death in Bergman’s Seventh Seal. The character of Davros—part Dalek and part mutated human—was a great success, scared the kiddies, and returned many times. The Daleks were filmed in partial darkness and low angles to make them even more creepy. The Kaleds who followed Davros were clearly supposed to be Nazis—one even wore an Iron Cross with his pince-nez glasses. Much is made of the Doctor’s moral agonizing over genocide, and the story was allegedly influenced by Hamlet and The Brothers Karamazov. This version of the genesis of the Daleks varies quite a bit from the original origin story as presented in The Daleks, second story of the William Hartnell years.