A female vampire must bathe in the blood of virgins in order to stay alive. The trouble is that virgins are in short supply nowadays, and she is running into major problems in finding one.
Berthe, a pretty young woman, has suffered from a mental disease since she was a child. A doctor has tried for years to understand her behavior and to teach her some basic notions such as those of time and emotional expression. But he also tends to use her as a guinea-pig and does not oppose her...
