Upon completing his graduate thesis, Kevin Parson is forced to face his own dark past when he is targeted by the psychopathic Riddle Killer. Following a terrifying encounter, in which he is given seconds to confess before his car is blown to bits, Kevin meets up with a criminal psychologist whose brother was killed in a similarly explosive confrontation. Together they must solve Kevin's mystifying riddle and uncover his connection to the murderer before he strikes again.