The TARDIS crew arrive on the Telos where they meet an archaeological expedition.  They are trying to gain access to the lost tombs of the Cybermen.  Once they enter the tombs, two of the expedition reveal that they are planning to revive the Cybermen.  They want to create an invincible army but it is revealed that the tomb is actually a conversion center to back new Cybermen.  The Doctor defeats the revived Cybermen and reseals them in their the tombs.