In the aftermath of an apartment fire, Missouri firefighters discover the body of 23-year-old single mom Melanie Breckle. It's clear she was the victim of a violent assault, and that her killer lit the fire to cover his tracks.

In Ottawa, a mother of three is stabbed to death in her suburban home. Solving the tragic homicide involves connecting cellphone records, a hidden camera, a fragment of a latex glove-and getting a DNA sample from a cold-blooded killer.