The murder of teacher's aide leaves a hole in the heart of her small community; as rumors spread about suspects, the actual perpetrator slips further away.

Father and teacher are found hanging naked from a tree with the letters F-E-D on his chest; with barely any evidence to work with, investigators turn to these letters for answers.

A single mom vanishes without a trace; foul play is confirmed when a truck toolbox opens with her body inside; homicide detectives investigate men she matched on dating sites, men from work, and a lover with a violent past.

A 20-year-old woman sets out on her bike and never returns; her body is found a few miles from her house with a gunshot wound to the head; years go by without any evidence or leads, until new investigators and technology breaks the case.

A navy lieutenant is murdered while deployed out to sea; arsenic poisoning is the cause of death; investigators discover he had more than his fair share of enemies, but it takes years before investigators discover what really happened to him.

A building manager finds the lifeless body of a young woman in the bathtub; when questioned, an ex-con living downstairs lies to police; the lies do not prove murder and the case goes cold, then a new forensic tool examines the evidence.