Dr Susan King was a psychologist and a field agent for the Ministry of Intelligence in the 21st century. At one point, she was in a relationship with James Baron, but ended it because she did not love him.
One day on assignment she discovered that Baron's employees were dealing in illegal arms shipments. She was assigned to work with the Fourth Doctor to infiltrate Baron Enterprises, and discovered that Baron was behind the arms shipments. She killed Baron when he threatened to shoot the Doctor. (PROSE: The Baron Wastes)