Transsiberian

An American couple, Roy and Jessie, decide to return home the long way from their recent sojourn in Peking and meet another couple from the West, Carlos and Abby, with whom they quickly form that tenuous bond that often unites fellow travelers away from home. When Roy gets separated from the train at a stopover, Jessie begins to realize that their compatriots aren't exactly who or what they seem to be.