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…

The Cybermen are on the march. The last remaining humans are hunted down. Lies are exposed, truths are revealed, and for the Doctor nothing will ever be the same.