Trainee doctor Martha Jones has her hands full balancing her medical studies with placating her demanding family. So the last thing she needs is to find that the hospital where she works has been transported to the moon, where it's invaded by an overbearing alien police force. There she encounters a patient called John Smith, who seems curiously at ease with the situation…

Whilst attending a carnival on the Chino-planet of Shan Shen, Donna is cajoled into having her fortune read, where her past is carefully examined. With the Doctor missing, Donna must work with Rose, a traveller from a parallel universe, to prevent darkness encompassing the whole of the universe.