It was her tenth birthday on Isis. By Earth years, she would be sixteen. But Olwen Pendennis had never been to Earth. She had been born on Isis. And since her parents' death, she had lived there alone, manning the Isis Light -- a "lighthouse" in space designed to aid ships, and to bring settlers from Earth. And now, on the day of her tenth year, the settlers are coming at last. Olwen is ready to welcome them, but are they ready for her? She was once human, like them. But the harsh climate of the alien planet has changed her, transformed her into something else -- something the settlers could never be prepared for...