Lupton forms an alliance with the spider to steal the Doctor's blue crystal, while Sarah and Mike attempt to alert people to what they've seen.

The Doctor and Sarah head to the meditation centre to try and get the crystal back while Lupton prepares to return it to Metebelis Three. But all their plans are disrupted when it is stolen by Tommy.

Sarah is captured by the spiders' guards while the Doctor tries to help Arak and the others strike back against the spiders.

The Doctor escapes from the spiders' larder only to encounter the Great One, while Sarah makes a deal with the Queen Spider.

K'Anpo persuades the Doctor he must face his fear and return the crystal to the Great One.But first they need to get past Barnes and his men.