In the castle on Sylvaniar, the Doctor and CaptainKrogh discover a Cyberman with a human arm and leg attacking Director Rukh. Krogh's attack is easily deflected, but when two guards enter with the recently attacked Dr Sovak, the Cyberman flees through a curtain. The curtain is against a solid wall, but the Doctor finds a secret passage. Dr Kravaal follows the Doctor and Krogh through the passage. The three find Dr Sovak manufacturing Cybermen in a secret laboratory. Sovak, who had faked his earlier attack, explains that some peasants took him to a crashed space vessel, where he discovered four damaged Cybermen. He has been rebuilding them with body parts taken from the kidnapped peasants.
Sovak orders his Cybermen to attack so he can control the castle, but he and they are electrocuted. Kravaal explains Sovak always had a problem with "heavy duty electrics". The electrics have caused a fire in the castle, and the Doctor frees Peri and Frobisher so they can escape in the TARDIS. Unfortunately, Frobisher reveals he is suffering from mono-morphia and is stuck as a penguin.