In 1956, a band of international refugees flee Budapest, escaping the bloodshed of the Hungarian uprising. Among them are Lady Diana Ashmore (Deborah Kerr) and her lover, Hungarian Paul Kedes (Jason Robards), who is forced to hide both his nationality and the wound he suffered in a street battle. The frightened refugees are halted at the Austrian border by Soviet Major Surov (Yul Brynner). Surov finds himself drawn to Diana as he interrogates the refugees in a hunt for suspicious persons. If Paul is discovered, everyone's life may be in danger.

The two romantic leads in this standard but well-acted political drama renew a famous pairing that began with THE KING AND I in 1956. Deborah Kerr is Lady Diana Ashmore, caught at the wrong side of the Hungarian-Austrian border in 1956, and Yul Brynner is Major Surov, a Russian commander who works at the border crossing. With the outbreak of the 1956 rebellion, the Budapest airport is shut down and Diana, along with other international travellers, are forced to reach Vienna by bus. Along for the ride is one of the Hungarian dissenters hunted by the police, Paul (Jason Robards, Jr. in his screen debut). Diana and Paul are in love and she is determined to protect his secret. Major Surov suspects a rebel is hidden on the bus, but he does not know which passenger is the guilty one. As interaction continues at the border, Diana is attracted to the Major and his complex character, even against her will. Their developing relationship and strong personalities carry the story from start to finish.