The TARDIS arrives on the planet Telos, where an Earth archaeological expedition led by Professor Parry is trying to uncover the lost tombs of the Cybermen. With a lot of help from the Doctor, the archaeologists enter the tombs. There, one of the party, Klieg, reveals himself and his business partner, Kaftan, to be planning to revive the Cybermen. He wants to use their strength, allied with the intelligence of his own Brotherhood of Logicians, to create an invincible force for conquest. It transpires, however, that the tomb is actually a giant trap designed to lure humans suitable for conversion into Cybermen - a fate that almost befalls Kaftan's assistant Toberman. After fending off an attack by Cybermats - small but dangerous cybernetic creatures - the Doctor destroys the Controller, defeats his revived Cybermen and reseals the tombs.