The Doctor tries to get everyone to Rio, but nothing quite goes as
planned. They arrive in a small Welsh village where the Doctor
immediately senses that the ground isn't quite right. There is a
drilling rig nearby that has reached a depth of 21 kilometers when odd
things begin to happen. A local village man has disappeared and soon
after Amy is swallowed into the ground. The Doctor realizes that the
drilling has disturbed an ancient reptilian race that has lived deep
underground for thousands upon thousands of years and who are determined
to protect themselves ...
