THE DOCTOR BRINGS ACE TO GABRIEL CHASE, Perivale, in 1883. The house is occupied by Josiah Samuel Smith, who keeps the domestic staff in a comatose state behind the walls and a creature locked up in the cellar.
Also in the house are Redvers Fenn-Cooper, a famous explorer who has lost his mind, and Ernest Matthews, a clergyman who has travelled from Oxford to challenge Smith over his “blasphemous” Darwinian theories.