After leaving the British Secret Service, David Somers finds work catalouging butterflies at the country house of Nicholas and Jess Fenton. After the murder of a local gamekeeper, suspicion falls on their niece, Sophie Malraux. Somers helps Sophie to escape arrest and they go on the run together.
| Actor | Role |
|---|---|
 Jean SimmonsSophie Malraux | Sophie Malraux |
 Trevor HowardMaj. David Somers | Maj. David Somers |
 Sonia DresdelJess Fenton | Jess Fenton |
 Barry JonesNicholas Fenton | Nicholas Fenton |
 Kenneth MoreWilly Shepley | Willy Shepley |
 Geoffrey KeenPolice Inspector | Police Inspector |
 André MorellSecret Service Chief Chubb (as Andre Morell) | Secret Service Chief Chubb (as Andre Morell) |
 Michael BrennanPolice Superintendent | Police Superintendent |
 Gerard HeinzDr. Karl Cesare | Dr. Karl Cesare |
| LLily KannMinna Cesare | Minna Cesare |
 Eric PohlmannTaxidermist | Taxidermist |
 Richard WattisEmployment Agent | Employment Agent |
 Sandra DorneKyra | Kyra |
 Maire O'NeillNora | Nora |
 Maxwell ReedHick | Hick |
 Marianne StoneYoung Woman at Nora's House (uncredited) | Young Woman at Nora's House (uncredited) |