Lowrie and Shen are the youngest people on the planet after a virus caused global infertility. Closeted in a pocket of London and doted upon by a small, ageing community, the pair spend their days mudlarking and looking for treasure - until a secret is uncovered that threatens not only their family but humanity's entire existence. Now Lowrie and Shen face an impossible choice: in the quiet at the end of the world, they must decide what to sacrifice to save the whole human race...