This film has mental illness written all over it’s facade of fear and illusion.
It is a brief stint into the falling apart of a family that has suffered, throughout decades of familial history, with mental health issues. You see this in the reading at the grandmothers funeral, when the mother(Annie) is reading about her mother..(it cleary got passed down to her daughter)..
The son, Peter, enters a fantasy nightmare world for the guilt of having been the reason his little sister died. She actually does die from a “nut” allergy at the party. Nuts allude to the fact that the family is nuts.
However, in Peters feeble mind, it is portrayed as a decapitation, while his sister, Charlie, is sticking her head out of the window of his mother’s car, which he is driving.
His mother becomes exceedingly disturbed after this and becomes abusive toward Peter. She blames him for the death of his sister. Even though she had insisted that his sister go to the party with him, although Charlie(the sister) did not want to go.
This movie is about the downfall and destruction of a family that has a history of severe mental illness, and their ultimate demise.