The Moonbase — Gerry Davis

Patrick Troughton plays the second Doctor in this four-episode adventure from 1967, set on the Moon and featuring a return appearance by the emotionless Cybermen.

The year is 2070, and Earth's weather is controlled by a device called the Gravitron, based on the moon and manned by an international team of experts. The TARDIS arrives to find the base in the grip of a plague epidemic which is drastically reducing the personnel. Before long an even greater menace is proved to be responsible--an invasion force from the planet Mondas, home of the Cybermen!