Miss Garrett was the computer specialist at the base. When the base crew couldn't solve the computer problems with the ioniser, she secretly left the base to find estranged scientist Elric Penley to try to convince him to come back. When he refused, she pulled a gun on him, but she was disarmed by Penley's friend Storr.
When the Ice Warriors invaded the control room of the base, Varga ordered her to shut down the ioniser, because it could destroy his ship. She and Leader Clent tried to convince him it couldn't be done, but gave in when Varga threatened to kill both of them. When the Doctor forced the Ice Warriors to leave the base, she turned the ioniser back on but didn't want to use it without the computer's approval. (TV: The Ice Warriors)