The TARDIS brings the First Doctor and his friends to a space tracking station in the Antarctic - and straight into trouble. A space mission is going badly wrong, and a new planet has appeared in the sky.

Mondas, ancient fabled twin planet of Earth, has returned. Soon its inhabitants arrive. But while they used to be just like the humans of Earth, now they are very different. Devoid of emotions, their bodies replaced with plastic and steel, the Cybermen are here.

Humanity needs all the help it can get, but the one man who seems to know what is going on is terminally ill. As the Cybermen take over, the Doctor is dying...