A tourist witnesses a murder and finds herself caught up in a series of bloody killings.
You can now watch The Girl Who Knew Too Much online on the following streaming providers in the United States.
| Camera | Mario Bava | Director of Photography |
| Sound | Roberto Nicolosi | Original Music Composer |
| Directing | Mario Bava | Director |
| Art | Luigi D'Andria | Set Decoration |
| Costume & Make-Up | Tina Grani | Costume Design |
| Directing | Enrico Checchi | Second Assistant Director |
| Writing | Mario Bava | Screenplay |
| Production | Salvatore Billitteri | Associate Producer |
| Editing | Lina Caterini | Assistant Editor |
| Editing | Mario Serandrei | Editor |
| Art | Giorgio Giovannini | Art Direction |
| Production | Paolo Mercuri | Production Manager |
| Writing | Ennio De Concini | Story |
| Writing | Sergio Corbucci | Screenplay |
| Production | Armando Govoni | Production Assistant |
| Writing | Eliana De Sabata | Story |
| Writing | Franco Prosperi | Screenplay |
| Costume & Make-Up | Mara Rocchetti | Hair Designer |
| Writing | Mino Guerrini | Screenplay |
| Production | Massimo De Rita | Executive Producer |
| Writing | Ennio De Concini | Screenplay |
| Writing | Sergio Corbucci | Story |
| Writing | Eliana De Sabata | Screenplay |
| Directing | Franco Prosperi | Assistant Director |
| Camera | Ubaldo Terzano | Camera Operator |
| Directing | Neda Matteucci | Script Supervisor |
| Costume & Make-Up | Euclide Santoli | Makeup Artist |
| Art | Emilio Schuberth | Set Dresser |
| Lighting | Antonio Rinaldi | Gaffer |
