With the Doctor frozen by the energy release from the barrow, Jo calls Yates and Benton for help, but when the Brigadier tries to join them he finds the village surrounded by a heat barrier.
Quest roles:
Richard Franklin(Mike Yates), Nicholas Courtney(Brig. Lethbridge-Stewart), John Levene(Sergeant Benton), Roger Delgado(The Master), Damaris Hayman(Miss Hawthorne), Don McKillop(Bert the Landlord), Rollo Gamble(Winstanley), James Snell(Harry), John Joyce(Garvin), Eric Hillyard(Dr. Reeves), Jon Croft(Tom Girton), Christopher Wray(Ldg. Seaman Lovell), Gerald Taylor(Baker's Man), Stanley Mason(Bok)