Doctor Who: Genesis of the Cybermen

A King lies dying in his castle. His eldest son Prince Sylvan is an artist with no desire to inherit a kingdom, while Prince Dega toils in his laboratory, dedicated to saving their dying people from extinction. They will all burn unless he succeeds.

When the TARDIS arrives, its crew believe they can help. But this planet is Mondas. And this is the Genesis of the Cybermen...