Parasitic twins are a rare phenomenon in which one conjoined embryo develops normally while the other becomes a partial, unconscious body. Chip is the so-called normal twin, but he is dominated by Chaz, the incomplete parasitic twin who does not exist as his own entity.

Yet it is Chaz who dominates and directs Chip along a path of murder and horror. Whether Chaz is a figment of Chip's deeply disturbed imagination or actually exists is unknown. Chaz's jealousy toward Chip and Chip's survivor's guilt make a lethal combination in which our assumptions about what it means to be alive are challenged. Each of us has an inner voice that directs us on our life journey. In Chip's case the path is a bloody and insane nightmare, as he struggles to overcome his inner demons.