S1 • E4 Apr 20, 2013 14m
When something threatens The Doctor's existence by pulling the Doctor's second incarnation out of time and causing a threat to the Doctor's timeline. Both Doctor's need to figure what is happening and stop the threat to their timeline and their existence. it is never a good idea for the Doctor to cross his own time stream but sometimes it's inevitable and now it is threatening his very existence in the universe.
