Katharine Hepburn plays a humourless Russian, Captain Vinka Kovelenko, who defects from her home country. Major Chuck Lockwood, played by Bob Hope, is assigned to show her the bright lights of London while she tries to convince him of the superiority of communism. Naturally, the two opposites fall in love but then must contend with the KGB who are not happy with the idea of one of their officers running around free in London.