The  tough no-nonsense Commander of Bowie Base One, the first earth mission sent to Mars. The Doctor shows up just as the Flood have infiltrated the base. Despite efforts to contain the wet lifeform, Adelaide and her crew are quickly overrun by the creatures. After the loss of several of her crew members, Adelaide realizes she can't let the Flood get to Earth. She is determined to use any measures to stop them, including using a nuclear device, sacrificing herself and her remaining crew.

The Doctor knows thats how history records their deaths. In fact, Adelaide's own granddaughter will be inspired by her grandmother's sacrifice to go on to accomplish even greater deeds. The Doctor, however, decides this time he is going to change history. Despite this being a fixed point in time, the Doctor ignores the laws of time and transports Adelaide away from the explosion and back to safety on earth. Realizing that the Doctor has just changed hers and possibly her granddaughter's destiny, Adelaide shoots herself rather than risk altering the course of history.