Ted Hutchens (David Knight) works as a code expert for US intelligence at the American Embassy in London. On a night off he visits the ballet and has a chance meeting with a beautiful woman, Anna (Odile Versois), and falls in love with her. Anna is the daughter of a Russian diplomat and Ted soon realises the risk to his career if the relationship continues. At the US Embassy the staff are warned about counter espionage and Ted's phone is tapped as part of the ever tightening security. Meanwhile Anna's father discovers her relationship with Ted and when he realises she is pregnant dispatches her back to Russia. Once Ted's love for Anna is discovered by his employers they have only one choice, to try to escape from both sides!