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.
| Production | Gerry Fisher | Producer |
| Editing | Brian Smedley-Aston | Editor |
| Production | Herbert Brodkin | Producer |
| Directing | David Greene | Director |
| Production | Michael Powell | Producer |
| Writing | Gerald Vaughan-Hughes | Screenplay |
| Art | Richard Williams | Opening Title Sequence |
| Art | Wilfred Shingleton | Production Design |
| Art | Terence Morgan | Set Decoration |
| Production | Clifton Brandon | Production Manager |
| Directing | Ann Skinner | Continuity |
| Production | John Pellatt | Associate Producer |
| Art | Fred Carter | Art Direction |
| Production | Edith Hamlin | Casting |
| Art | Terence Morgan II | Set Dresser |
| Writing | Leo Marks | Story |
| Camera | Wally Byatt | Focus Puller |
| Costume & Make-Up | Gladys Leakey | Hairdresser |
| Camera | Jimmy Turrell | Camera Operator |
| Costume & Make-Up | Bridget Sellers | Wardrobe Master |
| Art | Alf Pegley | Property Master |
| Sound | Don Challis | Sound Editor |
| Editing | Keith Palmer | Assistant Editor |
| Editing | Jimmy Turrell | Assistant Editor |
| Costume & Make-Up | Bob Lawrance | Makeup Artist |
| Directing | Zelda Barron | Continuity |
| Directing | Gordon Gilbert | Assistant Director |
| Sound | H.L. Bird | Sound |
| Sound | Tristram Cary | Sound Effects |
| Costume & Make-Up | Sue Yelland | Costume Consultant |
| Sound | Gerry Humphreys | Sound |
| Camera | Gerry Fisher | Director of Photography |
| Sound | Jerry Goldsmith | Original Music Composer |
