Skara Brae, Orkney, the end of the Stone Age. The sun is dying, storms batter the coast and people fear the end of the world. When Rab crawls out of the sea wearing the remains of his Silver Skin, he throws the islanders into confusion. Who is he? Why has he come? Voy, the village wise woman, is certain he's a selkie, a source of new power. Cait isn't so sure. Rab, thousands of years from home, injured and desperate, must learn fast about this ancient world. What started as a high-tech study trip has turned into a struggle to survive.