Intensity

Though not explained in the movie, the novel goes into further depths about Vess and his background, namely that as a young child, he developed sociopathic and sadistic tendencies and began torturing and killing animals. When he was nine, Vess' parents caught on to his violence and attempted to seek help for him. In response, he set fire to their home, killing them both. The fire was ruled an accident and Vess was assumed to be a traumatized survivor.

Vess was then placed in the custody of his grandmother, where he stayed for two years before stabbing her to death in a fit of anger. After this, he was placed in a youth home for just over a year before his record was expunged and he was adopted out to another family, who had no knowledge of his crimes. Vess lived with this family until he was twenty, at which point he killed them in another arson fire for their inheritance.

When Chyna throws herself down the stairs to break the chair she's chained to, you can see both of her hands come free as she's falling. But when she lands at the bottom of the staircase they are connected again.

Referenced in Piège en profondeur (2000)