Caris was a Tigellan Savant. Caris advocated the reclaiming of Tigella’s surface from the dangerous plants which lived there. Caris led Meglos into the city while he was disguised as the Fourth Doctor. Along with Lexa, Caris alerted Zastor to the theft of the Dodecahedron. The real Doctor was blamed for the theft. With Deedrix, she theorised on its disappearance.
Meglos approached her and forced her to come with him. He told her of his true identity and had her obey him by showing her the impossible, the shrunken Dodecahedron.
Caris tried to tell him that he could not escape now with the city doors closed. He told her that there were ventilation shafts.
Caris took Meglos prisoner with a gun when he was distracted. She led him through the city. Believing Meglos to be The Doctor, Romana II hit Caris, dazing her. Meglos ran away. Caris told Romana that it was not Meglos whom she saw. Together, they began searching for The Doctor.
Caris joined The Doctor, Romana, Deedrix and K9 as they travelled in his TARDIS to Zolfa-Thura. The Doctor left them to seek out Meglos and was captured. She helped rescue him and they left as Zolfa-Thura was destroyed. The Doctor then returned her to Tigella. (Meglos)