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 against the 'apes' who live on the surface. Written by
Did You Know?
A fifth doctor story, Doctor Who: Frontios: Part One
(1984), also featured creatures pulling people through the Earth below. Those creatures, the Tractators, are not related to ones in this episode. See more
Oh please, have you always been this disgusting?
No. That's recent.
Doctor Who Theme
Written by Ron Grainer
Arranged by Murray Gold
Performed by BBC National Orchestra of Wales See more