Two couples are stranded on Russia's east coast in the year of 1840, and their only option is a desperate attempt to cross the vast wilderness of Siberia to return to civilization. Survival is jeopardized by harrowing encounters with Cossacks, Manchu, escaped convicts and ultimately, Tsar Nicholas whose men pursue the castaways for murders tied to a Romanov conspiracy involving a giant ruby known as the Antares. Historically accurate events provide non-stop suspense.