Octave Verbrugge, a powerful Belgian building contractor, met Hugo Saint-Laurent, a brilliant French engineer, during a business trip and made friends with him. Now that his bureau of expertise is experiencing difficulties with one of their important projects he has the idea to hire his friend to help resolve the problem. Hugo agrees and stays as a guest at Octave's home in Ghent, where the promoter lives with his two unmarried sisters, Françoise, a beautiful but mysterious woman, and Aurélie, a very strict and withdrawn lady.
| Actor | Role |
|---|---|
| NNand BaertRobert Van Loo | Robert Van Loo |
| RRoger BoldersOctave Verbrugge | Octave Verbrugge |
| JJean DaskalidèsOmer Van Acker | Omer Van Acker |
| EEdgard de PontLe concierge de l'hôtel | Le concierge de l'hôtel |
| GGaston DesmedtHendrik Veys | Hendrik Veys |
| SSylvie IvensMademoiselle Ivens | Mademoiselle Ivens |
| PPascale KellenSekretaresse | Sekretaresse |
| MMabelaLa danseuse vaudou | La danseuse vaudou |
| HHélène MatthijsL'infirmière d'Aurélie | L'infirmière d'Aurélie |
 Marie-José NatNot listed | Not listed |
| GGus PrilsNot listed | Not listed |
| RRené PrévelNot listed | Not listed |
| PPros VerbruggenInspekteur Léonard | Inspekteur Léonard |
| OOswald VersypLe psychiatre | Le psychiatre |
| NNini De RaveBourgeoise | Bourgeoise |
| YYvette MerlinBourgeoise | Bourgeoise |
| Marie-José NatFrançoise Verbrugge | Françoise Verbrugge |