During the Cold War, the chief of a British intelligence code-breaking section falls in love with a new employee and shields an old co-worker accused of Communist affiliations from the wrath of the security branch.

British mathematician Sebastian (Sir Dirk Bogarde), working on code decryption, unexpectedly falls in love with decrypter Rebecca Howard (Susannah York). This leads them to a complicated intrigue within the codebreakers.—Steve Crook <[email protected]>