After a chance meeting and an indiscreet conversation, childhood friends Tommy Beresford and Tuppence Cowley become involved in a convoluted intrigue led by a mysterious man known simply as Mr. Brown.
Unfortunately the movie The Secret Adversary is not yet available on HBO Max.
| Directing | Tony Wharmby | Director |
| Writing | Agatha Christie | Novel |
| Production | Corinne Rodriguez | Casting |
| Production | Peter McKay | Production Manager |
| Directing | John Quilty | First Assistant Director |
| Directing | Bill Challoner | Second Assistant Director |
| Camera | Geoff Harrison | Camera Operator |
| Sound | Reg Mills | Sound Recordist |
| Production | Lynda Ostermeyer | Production Assistant |
| Directing | Lynda Ostermeyer | Continuity |
| Art | James Dillon | Production Design |
| Costume & Make-Up | Penny Lowe | Costume Designer |
| Art | John Tribe | Graphic Designer |
| Costume & Make-Up | Pauline Boulton | Makeup Supervisor |
| Directing | Philip Chambers | Stage Director |
| Lighting | Joe Spence | Gaffer |
| Production | Brian Kelly | Location Manager |
| Sound | Charlie McFadden | Boom Operator |
| Camera | Tony Cridlin | Grip |
| Camera | Dennis Rogers | Grip |
| Directing | Graeme Perry | Third Assistant Director |
| Art | Peter Bloxham | Property Buyer |
| Writing | Pat Sandys | Screenplay |
| Sound | Joseph Horovitz | Original Music Composer |
| Art | Bryan Bagge | Production Design |
| Camera | Mike Humphreys | Director of Photography |
| Editing | Ray Helm | Editor |
| Production | Ron Fry | Associate Producer |
| Production | Jack Williams | Producer |
