The Wheel in Space

From http://www.bbc.co.uk/doctorwho/classic/episodeguide:

The TARDIS materialises on board a spaceship, the Silver Carrier, where the Doctor and Jamie are attacked by a Servo Robot. Jamie manages to contact a nearby space station known as the Wheel and they are rescued. Meanwhile, the Silver Carrier discharges some Cybermats, which also travel to and enter the station. These pave the way for the penetration of the station by Cybermen, who intend to use its direct radio link with Earth as a beacon for their invasion fleet.

The Doctor sends Jamie and a young woman named Zoe Heriot over to the Silver Carrier to fetch the TARDIS's vector generator rod. Meanwhile he manages to free the Wheel's crew from the Cybermen's hypnotic control and to destroy all the Cybermen on the station.

When Jamie and Zoe return, he installs the rod in the station's X-ray laser, making it powerful enough to destroy the Cyber-fleet. An approaching force of space-walking Cybermen is also vanquished.

3 out of 70 (4.3%) raters say this story requires a previous story.