Ep 6. Love Bites

A vivacious teenage girl is found brutally stabbed to death in her car in a small Pennsylvania city. The motive is elusive; she wasn't sexually assaulted, and she was happy and popular. But as police look closer, they discover she was involved in a shocking love triangle that breaks all the rules. When the suspects' stories overlap and raise more questions than they answer, investigators turn to forensics to separate the lies from the startling truth. One tenacious detective goes to surprising lengths to obtain that evidence, and in the end, in a dramatic twist, it's the victim herself who gives police what they need.