A tour group visits a preserved plague pit, and a four-year-old girl slips away while the guide isn't looking. The poem piles up the grim details of the Black Death, with its fleas, swollen buboes, tolling bells and half of London dead, then swerves into the guide's oddly upbeat facts: more jobs, higher wages, an end to the war, people speaking "real English." Death turns into a lesson about economic silver linings.
Then the mother's shout, "Kelsie, get your butt over here!", drops the poem into the present. The speaker seems to watch with quiet amusement and a little tenderness. Calling the mother "an apologetic angel" is funny, but it also hints at rescue from the dead. The adults laugh and marvel that a child would play there, yet the poem leaves us wondering who is really being odd. A small girl treating a grave as a playground might be the least strange response in the room. The mood is wry, light on top and shadowed underneath.