De Britse wiskundige Sebastian werkt voor de Britse overheid aan het ontcijferen van vijandelijke codes. Hij wordt verliefd op zijn collega Rebecca Howard, maar als zij hem na een tijdje verlaat, ziet Sebastian zijn werk niet meer zitten.
Nee, helaas is Sebastian nog niet beschikbaar op Netflix in Nederland.
| Editing | Brian Smedley-Aston | Editor |
| Production | Michael Powell | Producer |
| Directing | David Greene | Director |
| Production | Gerry Fisher | Producer |
| Production | Herbert Brodkin | Producer |
| Writing | Gerald Vaughan-Hughes | Screenplay |
| Art | Richard Williams | Opening Title Sequence |
| Production | Edith Hamlin | Casting |
| Art | Fred Carter | Art Direction |
| Art | Alf Pegley | Property Master |
| Sound | H.L. Bird | Sound |
| Directing | Zelda Barron | Continuity |
| Costume & Make-Up | Gladys Leakey | Hairdresser |
| Production | John Pellatt | Associate Producer |
| Sound | Don Challis | Sound Editor |
| Writing | Leo Marks | Story |
| Sound | Tristram Cary | Sound Effects |
| Costume & Make-Up | Sue Yelland | Costume Consultant |
| Costume & Make-Up | Bridget Sellers | Wardrobe Master |
| Camera | Jimmy Turrell | Camera Operator |
| Camera | Wally Byatt | Focus Puller |
| Art | Terence Morgan | Set Decoration |
| Directing | Ann Skinner | Continuity |
| Directing | Gordon Gilbert | Assistant Director |
| Art | Terence Morgan II | Set Dresser |
| Sound | Gerry Humphreys | Sound |
| Costume & Make-Up | Bob Lawrance | Makeup Artist |
| Editing | Keith Palmer | Assistant Editor |
| Editing | Jimmy Turrell | Assistant Editor |
| Art | Wilfred Shingleton | Production Design |
| Production | Clifton Brandon | Production Manager |
| Camera | Gerry Fisher | Director of Photography |
| Sound | Jerry Goldsmith | Original Music Composer |
