The Second Doctor: Patrick Troughton. Cybermen, Cybermats, Ice Warriors and Yeti feature in what is known as the monster season, the sonic screwdriver is introduced and we meet Alistair and Zoe.
The TARDIS arrives on Earth in the midst of a new ice age where Brittanicus Base is fighting a battle to force back the glaciers. A huge Ice Warrior is found frozen in the ice.
