Zanda was a Zodangan Red woman.
Her father was a lesser noble in Zodanga, who died when John Carter led the forces of the Thark in their attack against the city (as seen in A Princess of Mars). Her mother afterwards took the last pilgrimage down the River Iss because she could not live without her husband, and presumably died upon reaching the Valley Dor. Now orphaned and impoverished, Zanda developed a deep hatred for John Carter and lived only to avenge herself on him.
She eventually ended up as a slave in the house of Fal Sivas, living in constant fear of being used for his cruel experiments on living brains. It was while serving as a slave in his house that she met John Carter, who was posing under the name Vandor. Not knowing who he is, she quickly developed feelings for him and John Carter in return protected her from Fal Sivas.
Eventually, Zanda was selected by Fal Sivas to undergo brain surgery, but was rescued just in time by John Carter who came back because he needed Fal Sivas' spaceship to follow Gar Nal and Ur Jan, who had abducted Dejah Thoris, to Thuria. After being rescued she puts the other slaves out of their misery and personally takes down Fal Sivas. She then departs for Thuria along with "Vandor". On board of the ship she also meets Jat Or. On Thuria she is captured by the Tarids and imprisoned along with Dejah Thoris. She is later rescued by John Carter, Jat Or and Umka, helped by a reluctant Gar Nal and Ur Jan. She escapes with them while John Carter is recaptured.
When she sees John Carter again after he too escapes, she has learned about his true identity but has come to realize that he isn't so bad after all. Back on Barsoom she declares her love for Jat Or. The two were presumably married later.