Zoe Takes the Wheel
The Doctor & Jamie have said good-bye to Victoria when there's an emergency in the Tardis. The fluid link is faulty, this time for real, and explodes. Last time the fluid link was faulty the Doctor first ran into the Daleks. Leaving the Tardis they discover they have landed on a small unmanned craft, not far from a "Wheel In Space", a manned Earth space station.
As a result of an unexpected course change, the Doctor stumbles and bumps his head, knocking him out. (Patrick Troughton was on holiday during the filming of episode 2). Jamie is able to communicate with the Wheel and is rescued, but they consider the small ship a menace and attempt to blow it up. Knowing the Tardis is still there, Jamie sabotages the Wheels weapons.
A coming meteor storm means the Wheel is defenseless with the weapons damaged. The Doctor is able to convince the crew he is able to help, and not the enemy. He meets Zoe, an astrophysicist with a photographic memory. She has a high intelligence as a result of conditioning and considered to be smug and arrogant by most of the crew, as well as unemotional. But she is kind and caring.
The weapons are fixed and the asteroids destroyed but an even greater menace is discovered. The Cybermen have infiltrated the Wheel in Space and taken control of several key officers. In order to defeat the Cybermen the Doctor needs a device he left on the Tardis in the other ship. Jamie and Zoe are sent to retrieve it, narrowly missing being hit by additional asteroids.
It's discovered the Cybermen on the Wheel are only an advancement. A Cybership is looming. Their primary goal is to take full control of the Wheel. But with Jamie and Zoe having returned with the Doctors equipment, the Wheel is able to destroy the Cybership and blow all remaining Cybermen attempting to gain entry, back into space. The Doctor and Jamie depart, but someone tags along.
WHO: Zoe Herriot
PLANET OF ORIGIN: Earth, but met the Doctor on the Wheel In Space; 21st Century
REASON FOR JOINING: Sneaks aboard for a more adventurous life.
NEXT: The Invasive Cybermen