When George Hardy, surgeon and photographer, sets off from the cold squalor of Victorian Liverpool for the heat and glitter of the Bosphorus to offer his services in the Crimea, there straggles behind him a small caravan of devoted followers: Myrtle, his adoring adoptive sister; lapsed geologist Dr Potter; and photographer's assistant and sometime fire-eater Pompey Jones, driven onwards through a rising tide of death and disease by a shared and mysterious guilt.