Thomasine Heiner

The Doctor and Liz are summoned to the Wenley Moor Research Centre by the Brigadier, after several staff members suffer nervous breakdowns.

The Doctor attempts to convince people there are monsters in the caves, prompting Major Baker to start shooting at a reptile man.

The Silurians contact Quinn for help in retrieving their fellow while the Doctor and the Brigadier organise a search of the moors.

Worried about the Old Silurian's growing friendship with the Doctor, the Young Silurian has the scientist infect Baker with a virus and then release him.