Shahna was a drill thrall on the planet Triskelion, where she was born in the mid-23rd century. Her mother had previously been killed in a freestyle match.
In 2268, she was encountered by the crew of the USS Enterprise, who were kidnapped from their ship by the Providers. Shahna was responsible for training the new thralls, becoming romantically involved with Captain James T. Kirk in the process.
To free his crew, Kirk wagered with the Providers that he would fight and defeat three thralls at the same time. Two of the three were killed in competition with Kirk, but the third was only injured, and Shahna replaced this thrall. Competition continued and Kirk forced her to submit, but refused to kill her.
Following the defeat of the Providers, she requested to leave with the Enterprise, but her request was denied by Kirk, who thought it was better for her to stay there and learn a new way of life.