On a Newport beach in the summer of 1809, a boy half-asleep on the sand looks up to find a weeping stranger leaning on his cane at the water’s edge. The man calls himself Henri Baptiste, émigré of ’93, and what he then tells the boy is a confession he has carried across an ocean: how he walked a condemned prisoner through the gates of the Conciergerie, in borrowed rags, past the cart carrying Marie Antoinette to the guillotine.