On the planet Telos, an archeological expedition uncovers a hidden entrance in a mountainside. Whilst one of the members tries to open the doors, he is electrocuted. Moments later, the TARDIS lands nearby and the expedition is met by the Second Doctor, Jamie and Victoria. Parry, the expedition's leader, explains that they are here to find the remains of the Cybermen, who apparently died out five centuries before. The expedition is funded by Kaftan, who is accompanied by her manservant Toberman and her colleague Klieg. Deciding to accompany them, the Doctor helps open the doors and, whilst he, Parry and Klieg stay to open the hatch leading to the tombs, the others explore the building.