In the not too distant future, a one-hundred-year-old man called H sails the eastern coast of England with his godson. H recalls when he himself was sixteen - his godson's age - as they search for the site of H's life-altering friendship with a boy named Finn. Finn lives alone on an isolated slip of land and follows no rules: he spends his days swimming, fishing, and collecting driftwood for his tiny beach hut. H, on the other hand, is an upper-class boarding school boy stifled by monotony and endless rules.