It is the height of the Cold War. British Agent Steve Carradine's mission is to locate and smuggle to the West a defecting Russian scientist with the vital secret of a new technology - but the Soviets are hot on his trail. Aided by a mysterious female agent, Carradine finds Professor Ubyenkov, and the three fugitives make a desperate flight on the Orient Express in a superhuman effort to remain alive and escape to Britain.