A strange signal from Earth draws the TARDIS to the island of Lanzarote, where Turlough rescues a young American girl, Peri, from drowning. Among her possessions is an artefact bearing an alien symbol - the same triangular mark that Turlough has branded into his arm. The mystery deepens when Kamelion falls under the control of a powerful mind, and the TARDIS travels to the volcanic world of Sarn. As Turlough is forced to face his past, the Fifth Doctor must stop his oldest enemy from harnessing the revitalising powers of Numismaton gas...

Timon loves to give parties and objects to friends, but when he cannot pay his creditors, his "friends" refuse to help him, and he becomes a misanthropic hermit.

Helena loves Bertram, but he's of noble birth, while she's just a doctor's daughter. But Bertram is at the court of the King of France, who is ill, and Helena has a remedy that might cure him and win her the right to marry Bertram. But does Bertram want to marry her?

Children's drama series following the lives of students and teachers at Grange Hill comprehensive school.