English schoolboy and his Dutch pen friend chase a diamond smuggling gang in Holland.
| Actor | Role |
|---|---|
 Sean ScullyTim | Tim |
| JJacques VerbruggePiet | Piet |
| SSandra SpurrAnnike | Annike |
| WWalter RandallThe Guide | The Guide |
| TThom KellingVan Helder | Van Helder |
 Riek SchagenMrs. Van Helder | Mrs. Van Helder |
| PPaul OstraDiamond Cutter | Diamond Cutter |
 Sacco van der MadePolice Superintendent | Police Superintendent |
| JJean LemaireGrandpa | Grandpa |
| JJohn SoerMan in Blue | Man in Blue |
| GGerard DotingDutch Thug | Dutch Thug |
 Frans KokshoornDutch Thug | Dutch Thug |
| KK. BrouwerDutch Thug | Dutch Thug |
| JJohn RodenLondon Crook | London Crook |