Sari Martínez is making a solo trek across Antarctica, having left from Snowcap Base, when she hits a large blue box. After she recovers consciousness, she is relieved that she is unhurt and continues her journey
Suddenly, she is no longer able to make radio contact with Belgrano. At one point, she sees two planes, one chasing the other. Some time later, the sky goes black, even though the sun is still up. She also sees some strange pink wreckage.
As she gets close to Belgrano, she radios in and receives a message from Snowcap from someone called the Doctor. He explains that there was an attempted alien invasion by the Gelidons, but he and his friend Steven stopped it. Everyone from the base has been evacuated. However, the Gelidons are now coming after him. Sari decides to rescue the Doctor instead of finishing her journey and heads back to Snowcap.
After she finds him, they race across Antarctica, heading for the blue box. On the way, they are attacked by Gelidons but they make it to the TARDIS safely.
to be added
- Towards the end of his first incarnation, the Doctor would return to Antarctica in December 1986 in the company of Ben Jackson and Polly Wright. On that occasion, he encountered the Cybermen for the first time. The Doctor was able to defeat the Cybermen. However, the strain of the conflict led to his regeneration into the Second Doctor. (TV: The Tenth Planet)