This episode – The Invasion (1968)
The Second Doctor (Patrick Troughton), Jamie, and Zoe arrive in then-near-future now-very-past Earth and we meet UNIT for the first time! Good thing too, because some idiot named Tobias Vaughn and his lackey Packer (everyone say it all together now: PAH-kur!) really feel that what the Earth needs is a Cyber invasion. The Cybermen feel slighted in Vaughn’s stupid plan, and decide life on Earth should end. So it goes.
Andrew tries to access Vaughn’s secret room, but fails, which is too bad because that alarm is driving him nuts. Steve’s new emotion projection machine keeps burning out as Andrew tries to hold off the Cyber forces himself. Steve passes along some time circuits to Andrew – big mistake – but the two wind up passing out from an Invasion Marathon. Also: PAH-kur!