John Walsh profiles Juan Lazaro Abrego who is believed to have murdered his ex-girlfriend, a beloved schoolteacher; Callahan Walsh investigates Derek Dean, a St. Louis man accused of shooting identical twins, killing one and wounding the other.

John Walsh profiles John Blauvelt, a troubled U.S. Army vet who is accused of waging a lethal war against his young wife. Later, Callahan looks at Rudy Fernandez, whose teen romance with his high school sweetheart is believed to have turned deadly.