She had decided to "make a difference" by going into space after the death of her child, Claire, who had lived for seven days. She met the Fourth Doctor and Leela after Nerva became infected by a virus. They fled from the space station, together with Giles Moreau, aboard the supply ship Chandler, but were forced to abandon the craft in space suits as Moreau had been infected.
Foster, the Doctor and Leela were teleported by the Drellerans who revealed the virus was their design. They had suffered under Jack Corrigan and wanted to destroy humanity. Foster argued that her species had changed in the centuries since Corrigan's time, and the Doctor and Leela corroborated this. The Drellerans injected them with an anti-virus and returned them to Nerva. When they made contact with the infected, the virus was destroyed. (AUDIO: Destination: Nerva)