None know better than Dr Peter Edwards and his wife Sarah, who worked through the London pandemic of 1866, how quickly cholera can strike. When Countess Beletsky, her daughters and servants, and John's workers succumb, Peter fights for their lives tirelessly until he too falls victim.

The only doctor within a hundred miles is Nathan Kharber, a Jew distrusted by the Russians. Nathan knows if he fails to save his Christian patients, the Cossacks will hang him as they have other doctors of his faith for centuries.

While the immigrants wait to discover if Nathan can save Peter, Glyn, Richard, the Countess, and her daughters, John Hughes and Sarah Edwards both find themselves fighting an ignorance born in thousands of years of superstition on the Russian Steppes.