On the Planet Isopterus (comic story)

Summary
Tegan has a go at the Doctor's new dream machine and the TARDIS crashlands on the dying world of Isopterus. The travellers soon discover something is aiding the fall of Isopterus years before its destruction. The Doctor faces a dilemma: save Isopterus and change time or let history take its course and be the reason for a planet's end.

Characters

 * Fifth Doctor
 * Tegan Jovanka
 * Adric
 * Nyssa

Continuity
to be added