The film starts with the end as Helene Delambre killing her husband caught the attention of a fairly dim witted worker. This leads to detective Charas getting involved. Helene confesses the murder over the phone to her husband’s brother Francois Delambre. Francois tells the detective about the phone call. The detective then comes over to Helene house to question her. We then see that she is obsessed with flies and cried when the maid squashed one. The audience starts to think she is mad, as does the detective. Helene tells the story leading up to the murder. This is when the film gets more interesting. Helene a devoted house wife and Andre Delambre the husband have a happy normal life with a son until Andre makes a teleportation device and decides to go through. For some reason, unknown to the audience or Helene. He hides his face and hand. It is later discovered that a fly accidently got in with Andre and the transportation device fused them both together. Andre has the head and an arm of a fly. Andre tells Helene that the only way to save him is to find a white headed fly, which has the body of a fly with a human face, and get them both to go through the teleportation device again to turn them back to the original state. She fails however, and is forced to kill her husband before he loses control and his animal instincts kick in.
I though the film was rather good, excusing the bad acting skills. I like the way your perception of Helene changes throughout the film. At the beginning we see her as an evil murderer. But as time goes on we come to believe she is actually crazy. But towards the end, we understand why she killed her husband and start to sympathise towards her. Also Andre starts out as a kind gentle man, but then goes through the machine and becomes more aggressive and angry as time goes on. Maybe the fly within has already has started controlling him.
As it is an old film, and the mask for the fly was terrible, I do not believe it has helped me with the physical side of my moth human hybrid. And apart from the aggression, the personality traits were that of any other human, but a cool film, none the less.