While the storylines of both the book and movie are practically identical, the movie uses cinematic techniques and dialogue changes to overstate or change some controversial points in the book—changes that were made with Davies' approval. The screenplay adaptation of the book was by Howard Koch. Its musical score was by Max Steiner, its cinematography by Bert Glennon. The extensive montage sequences, which draw on footage from Soviet archives, were supervised by Don Siegel. The picture was produced and distributed by Warner Bros. Ambassador Davies appears and introduces the film as himself; he is then portrayed by Walter Huston. Ann Harding plays his wife Marjorie Davies, Gene Lockhart is Soviet foreign minister Vyacheslav Molotov, Henry Daniell his German counterpart Joachim von Ribbentrop, and Dudley Field Malone plays Winston Churchill. Most parts, bar those of Davies' family, are taken by character actors who look like the famous politicians they are representing.