Millicent Brown was one of Iziah Brown's six wives. They lived in Eternity, California. Peri had an ancestor named Iziah Brown, and when she met the family, she wondered if Millicent was her ancestor.
Iziah and his wives took Josh Larson and Peri to a cave to see the Fountain of Youth. They were surprised by the Master, who had been seeking the fountain to repair the injuries he sustained on Sarn. When Peri spilled some of the water, the dinosaur fossils in the cave turned into living dinosaurs and attacked everyone.
The party, except for Dana, escaped in the confusion. Back at home, they were attacked by the Master's hypnotised townspeople. The Fifth Doctor suggested they shock the people out of their hypnotism, so Millicent danced a can-can with Simone. (PROSE: A Town Called Eternity)