A writer of murder mysteries finds himself caught up in a string of murders in London.
| Actor | Role |
|---|---|
 Michael GoughEdmond Bancroft | Edmond Bancroft |
 June CunninghamJoan Berkley | Joan Berkley |
| GGraham CurnowRick | Rick |
 Shirley Anne FieldAngela Banks | Angela Banks |
 Geoffrey KeenSupt. Graham | Supt. Graham |
| GGerald AndersenDr. Ballan | Dr. Ballan |
| JJohn WarwickInsp. Lodge | Insp. Lodge |
 Beatrice VarleyAggie | Aggie |
 Austin TrevorCommissioner Wayne | Commissioner Wayne |
| MMalou PanteraPeggy | Peggy |
| HHoward GreeneTom Rivers | Tom Rivers |
| DDorinda StevensGail Dunlap | Gail Dunlap |
 Stuart SaundersStrength-Test Barker | Strength-Test Barker |
| HHilda BarryWoman in Hall | Woman in Hall |
 Nora GordonWoman in Hall | Woman in Hall |
 Vanda GodsellMiss Ashton | Miss Ashton |
| GGerald CaseBookshop Manager | Bookshop Manager |
| GGeoffrey DentonSergeant at Jail | Sergeant at Jail |
 Sydney BromleyNeighbour | Neighbour |
 John HarveyMan in Bookshop | Man in Bookshop |
 Carole Ann FordTeen in Hall of Mirrors (uncredited) | Teen in Hall of Mirrors (uncredited) |