Coulton Salt Mine: a rare environment for geological exploration on the North Yorkshire coast. The Doctor is fascinated by the experiments of Professor Medra on the Zechstein seabed, but Dodo is distracted. Didn’t her family settle in this part of Yorkshire?

As the Doctor delves deeper into the work of Professor Medra, Dodo is helped by security guard Mick Huff, who is concerned about the strange happenings in recent weeks. Who are the children that keep appearing around the mine workings? Why are local landmarks vanishing? And how can the bedrock of a geological ‘quiet place’ be screaming?