Vicki happened to stow away onboard the Dalek time machine when the Robot Doctor was created. She alerted the real Doctor, Ian and Barbara to its existence. By that point, the robot had already duped Barbara into believing it was the real Doctor, and nearly killed her. When the whole party met the Robot Doctor, the timing of the meeting was such that Ian, Barbara and Vicki couldn't tell which was the real Doctor and which was the robot. In the confusion, Ian attacked the real Doctor. The robot kept up the pretence and tried to persuade Ian to kill the real Doctor by smashing his head with a rock. Before Ian could do so, the robot made a fatal mistake and revealed that its knowledge of the Doctor's travelling was outdated by calling Vicki "Susan." Barbara immediately realised that it was in