Beachhead

In an attempt to recharge his batteries after his confrontation with the Eleven, the Doctor takes Liv and Helen to the sleepy English seaside village of Stegmoor. But they find the village in turmoil and, to make matters worse, their arrival uncovers a mystery from the Doctor's past which threatens the future safety of the planet. Can the Doctor prevent the Voord from invading Earth? And more importantly why have they come in the first place?