Natasha Stengos was a member of a group of people who tried to free their loved ones from the suspended animation chambers of Tranquil Repose on Necros.
With her friend Grigory she broke into TR and tried to take back her father, Arthur Stengos. She found he was replaced with a mannequin and later found him in a laboratory being turned into a Dalek by the Great Healer (Davros). She couldn't stand looking at him like that and killed him when he asked her to.
She and Grigory were then captured by security and interrogated by Takis and Lilt who wanted to mark her for the guards she killed. The Sixth Doctor later freed her and Grigory, and they told him what had happened to Stengos. The Doctor wanted them to destroy the lab and then meet him in reception.
They tried to destroy the incubators mutating human brains into Daleks by rigging them to explode, but their subsequent attempt to escape failed when a Dalek appeared hovering above them. Natasha tried to escape with Grigory but both of them were exterminated by the Dalek before it was seemingly destroyed by the exploding incubators. (TV: Revelation of the Daleks)
According to another account, the pair were attacked by three Daleks, while helping the Doctor sabotage Tranquil Repose's systems. Grigori was killed before the Daleks were destroyed by Natasha, though the injuries she received during the fight were fatal. Aware that she was mortally wounded, she used her last shot to commit suicide to avoid being converted into a Dalek like her father. She was just twenty-five years old when she died.
Her and Grigori's deaths were mourned by the Sixth Doctor, who was assured by Alex Sagovski that the pair of them had not died in vain, as their actions had helped to destroy Davros' Daleks. (PROSE: Revelation of the Daleks) Natasha's actions also helped to expose Davros' actions and put a stop to his operations, as well as bring about the ruination of Tranquil Repose's reputation and its total destruction. (TV: Revelation of the Daleks, PROSE: Revelation of the Daleks)
