| Denis Lavant | Alex |
| Juliette Binoche | Anna |
| Michel Piccoli | Marc |
| Hans Meyer | Hans |
| Julie Delpy | Lise |
| Carroll Brooks | The American woman |
| Hugo Pratt | Boris |
| Serge Reggiani | Charlie |
| Mireille Perrier | The young mother |
| Jerome Zucca | Thomas |
| Charles Schmitt | |
| Ralph Brown |
A sexually transmitted disease called STBO is sweeping the country; it's spread by having sex without emotional involvement, and most of its victims are teenagers who make love out of curiosity rather than commitment. While a serum that can treat the disease has been formulated, it's been locked away in an inaccessible government building. A woman hires a man to steal the serum.