Humankind has arrived on Moss to discover if any intelligent native life exists there, and to assess the planet, recently discovered by the Derac, a nomadic space-faring race, for development - and profit. Multi-coloured shapes of dancing light have been spotted; strange sounds are heard in the night; the researchers name them the Mossen and send for a linquist to ascertain if it is evidence of intelligent life.

Jewel Delis has accompanied her half-brother Paul to this verdant paradise. Her task is to help Paul decipher the strange language of the Mossen - but she has a secret mission too. A new law on Earth means the imminent massacre of all beasts great and small, so Jewel must discover if Moss holds the promise of sanctuary for the doomed animals - once humankind's beloved companions.

Time is running out for Jewel's creatures, but it might be running out for Humanity too: the Planet Moss, itself a living entity, is not sure it cares for any of the species currently living on its surface . . .