The discovery of a mass grave dating to London's 1665 plague sets off grisly but fascinating time-travel experiences for a modern schoolboy. Oliver knows nothing of the plague when workmen at a demolition site near his home unearth something scary and mysterious. He is, however, enthralled by the gruesome: ""Death. . .had always flirted with him in dreams and stories."" Thus he's a natural candidate for being drawn through his home's old cellar into the body of a younger child, Thomas, is which guise he experiences dreadful but authentic events: all the other members of his family die and are thrown into the fearful pit after being robbed by terrified workers who try to drown their fear in drink. Meanwhile, in the present, the ghost of Thomas (who survived, thanks to a generous act described in Pepys' diary) appears as an elderly boarder in Oliver's mother's rooming house, where he plays a role in Oliver's learning the truth about the past--and the difference between horror as a game and the human realities the game masks. A well-researched and skillfully plotted story that contains enough graphic details to please kids who would enjoy (like Oliver) a visit to London's ""London Dungeon""--yet that presents them with compassion, so that readers will understand that each of these skeletons represents ""a child like him. . .someone had loved them.