Call it Genesis of the Cybermen. This story features the Fifth Doctor and Nyssa arriving at a strange asteroid colony, where everyone lives underground and where Cybernetics are the coming thing. It turns out to be a colony of Mondasians, and the Doctor knows exactly whats going to happen to them. This is a great story, made better by the fact that theres no Cyberman version of Davros. This is just a story about desperate people trying hard to survive and doing whatever they think is needed, even if by doing so, they lose their humanity.