When the first humans came to settle the planet Pern, they did not come alone : intelligence enhance dolphins also crossed the stars to colonize the oceans of the new planet, while their human partners settled the vast continents. But then distract disaster struck in the form of Thread, deadly silver spores that fell like rain from the sky, devouring everything and everyone in their path. And as the human colonist streams of a new idyllic life shattered into a desperate struggle for survival, the dolphins were forgotten, left to make their own life in the seas of Pern.