The film is based on the actual events of the Portland Spy Ring trial in the U.K. A disgruntled Navy Clerk is transferred to a secret research establishment and is subsequently black-mailed/paid by Czech intelligence to procure secrets for them. … Bernard Lee, William Sylvester, Margaret Tyzack, David Kossoff, Nancy Nevinson, Thorley Walters, Gillian Lewis Added on Netflix 2023-06-02. Youtube Trailer