The Doctor is a Time Lord: a 900 year old alien with 2 hearts, part of a gifted civilization who mastered time travel. The Doctor saves planets for a living—more of a hobby actually, and the Doctor's very, very good at it.
A small fictional village in England is completely subdued by an alien presence for an entire day. Upon waking, it is discovered that numerous women in the town are pregnant.
In the days following her return from hospital, new mother Kate is rocked by finding her world altered beyond recognition.
