The Tardis lands on the war-torn distant planet of Messaline, where a sample of the Doctor's DNA is used to create his clone, a fiesty young woman determined to defend her new home. While Donna and Martha get to know the newcomer, their time-travelling friend remains distant, and worries he may no longer be the last of the Time Lords. Guest starring Georgia Moffett, whose real-life father Peter Davison played the Doctor in the early 1980s