The Queen, alarmed at the fighting, decides to withdraw with Sabor as her prisoner. Tuar wants to abandon the Doctor in the street to avoid the patrols, but Sarah refuses and finds that the Doctor is still alive. They take him in.
Barnes and the others meet, worried about Lupton's disappearance. Mike spies on them.
The Queen returns to find Lupton and his spider sitting in the chamber. They demand to be rewarded before they return the crystal. Their defiance angers the Queen and she puts off any decisions until after Sarah is caught.
Tommy goes into his cupboard and tries to read. His eye is caught by the crystal and its light fills his mind, making him pass out. When he wakes, he finds that he can suddenly read easily.
Tuar and and Arak discuss attacking the spiders, but are not sure what good it would do. The Doctor wakes enough to tell Sarah to bring him a machine from the TARDIS. Sarah sneaks out and reaches the TARDIS. But when she emerges, she is caught by Lupton. Arak slips out, grabs the machine and brings it back in. The Doctor then uses it to discharge the psychic energy, healing himself.
Tommy goes to the library and begins reading more advanced books.
Sarah is taken to the Spider's larder, where she is imprisoned with Sabor and bound in a web cocoon.
Mike has heard enough. He comes in to speak to Barnes but is knocked out by a panicked Moss.
In the morning, the Doctor talks to Arak and Tuar while Sarah talks to Sabor. They are told that 433 years earlier, their colony ship crashed on Metebelis III. A group of spiders were blown into the blue crystal mountain. The radiation from the crystals gave the spiders tremendous mental powers. They then enslaved the humans. They rule through terror, having recently wiped out a village.
The Doctor has the villagers gather stones. He eventually finds one that could potentially block the spiders' attacks. He equips the villagers and sets off to rescue Sarah. He gets into a fight with the guards and loses the machine. Lupton orders him destroyed but the Guard Captain has both Lupton and the Doctor taken prisoner on the Queen's orders.
Sarah is elated to see the Doctor arrive. But he is accompanied by two guards…