The Doctor and Jo manage to escape from the mine with a maggot egg but Stevens is determined to stop them analysing it.
Blood memories surface when an anthropologist responds in kind to a captive gorilla's primeval hatred. Two men debate the best way to kill vampires.
The Doctor and the Brigadier attempt to rescue Jo and Bert from the mine but Global Chemicals prove distinctly uncooperative.
The programme follows the beginnings of chemistry: from the techniques of ancient metallurgy in China and Japan to the mystical searchings of the alchemists.
A spurned plantation owner in the British West Indies enlists the power of voodoo to avenge himself against a romantic rival.
The wandering nomads cease their migrations and settle in townships, learning new skills.
While the Doctor plans a holiday to Metebelis Three, Jo and the Brigadier are intrigued by a mysterious death at a coal mine in Llanfairfach, which is being blamed on local company Global Chemicals.
A young wife in a remote country house finds herself in thrall to strange and insistent voices of the dead.
The Doctor and his friends prepare to refreeze the Dalek army but the Dalek Supreme has arrived on the planet determined to destroy them all.
As the ice retreats and the land flowers, Man the hunter turns to agriculture, domesticating plant and animal, imposing his will on the wild wheat and the horse.
The programme follows the changes in Man as he marches out of Africa, through desert and ice age, to leave the print of his hand in a dark Spanish cave.
The Doctor and his friends ambush two Daleks as part of their plan to get back into the city, but the Daleks are on the verge of unleashing their virus.
Ancient Warrior, an aged Indian accompanied by Caine, seeks burial in his sacred, ancestral land. But the burial site is located dead center in a violent, Indian-hating town called Purgatory.
The Doctor and his friends escape from the Dalek base, prompting the Daleks to devise a plan to wipe them out.
A gambler on a hot streak entrusts his winnings to Caine. But the money is stolen, the gambler is killed, and Caine seeks answers to the mysteries surrounding both events.
With the news that the Reynolds household will soon be numbering three and with Bill bragging about "ringing the bell," Eddie devises a plan to prove his manhood. Brace yourself for a master class in seduction.
The Doctor and Codal escape from their cell and meet up with the Thal commandos who are trying to get into the Dalek base.
The entire family suffers a crisis when Olivia is stricken with polio. Dr Vance prescribes the accepted treatment, but Olivia does not get better. John-Boy learns of a new treatment practiced by sister Kenny and the family tries it to success in time for the Easter service.
It's pay day at Grace Brothers and the staff realize that their money just doesn't go very far. An opportunity for a bonus arises when a customer loses a diamond and offers a £100 reward. Greed gets the better of everyone, except Mr. Grainger, and soon they're conspiring behind each others backs. Mr. Mash throws a wrench in the search after he damages a jeweled dress, causing a multitude of "diamonds" within the department.