Years into the future, three colony ships leave the overcrowded environs of Earth to establish a society on Pern, a planet orbiting the golden, G-type sun of Rukbat in the Sagittarian sector. After travelling for 15 years, the settlers finally arrive on their dream world. With new land to plough, new seas to sail and new lives to live, Pern is an idyll. But it is not to last long.
Soon after the new colony has been established, a deadly rain begins to fall. Thread, a mindless lifeform brought into Pern's orbit by the wandering Red Star, devours all organisms and is able to totally strip a cow - or human - in hardly any time at all.
In order to defend their planet, the settlers genetically alter a natural life-form, the fire-lizard. Already able to breathe fire and bond empathically with their owners, the new fire-lizards are able to speak clearly with their riders and are bigger than horses, designed to grow slightly with each generation until they are about 40 metres long.
Christened 'dragons' for their similarity to the creatures of Terran myth, the dragons and their riders are all that stand between Pern and oblivion. For thousands of years, they carry out their task, suffering injury and death without complaint and receiving little thanks.
