The Keeper was the leader of the Crimson Chapter of the Orbus Postramo cult. Her charge was to prepare for the arrival of aliens at the End of Days, heralded by a woman described in the Book of Tomorrows. (AUDIO: Buried Secrets)
The Crimson Chapter maintained multiple biotech and genetic research facilities under its public front, the Rechauffe Corporation (later renamed Mandrake Corp). The Keeper's intent was to produce a biological agent that could wipe out humanity when the End of Days was here.
Under the Keeper's direction, Hilda Winters was given the task of testing whether Sarah Jane Smith might be the herald they sought. However, Ms. Winters took it on as a personal vendetta instead, for which the Keeper had her killed. (AUDIO: Buried Secrets)
Becoming convinced that Sarah Jane was the herald, the Keeper then ordered Crimson Chapter member Will Sullivan to make contact with Sarah and gain her confidence. Once Sarah started interfering in the Chapter's business (including spoiling an Antarctic uranium scheme), she ordered Will to kill Sarah. This time the Keeper's agent refused. (AUDIO: Snow Blind)
The Keeper then had Sarah and her confidantes gathered together at the Pangbourne Scientific Lab, where final research was finished on a far more virulent strain of the Marberg virus. The Keeper infected Sarah with the virus, as well as a group of protesters outside the gates of the lab, then offered Sarah a choice: die a slow and painful death from the virus, or a quick death from being shot. (AUDIO: Fatal Consequences) Though Sarah agreed to die quickly, her companion Josh Townsend managed to reach the room and shoot the Keeper, killing her instantly. Sarah and the protesters received a cure for the virus soon after. (AUDIO: Dreamland)